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• How to Write a Literature Review | Guide, Examples, & Templates

How to Write a Literature Review | Guide, Examples, & Templates

Published on January 2, 2023 by Shona McCombes . Revised on September 11, 2023.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research that you can later apply to your paper, thesis, or dissertation topic .

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates, and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarize sources—it analyzes, synthesizes , and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

What is the purpose of a literature review, examples of literature reviews, step 1 – search for relevant literature, step 2 – evaluate and select sources, step 3 – identify themes, debates, and gaps, step 4 – outline your literature review’s structure, step 5 – write your literature review, free lecture slides, other interesting articles, frequently asked questions, introduction.

• Quick Run-through
• Step 1 & 2

When you write a thesis , dissertation , or research paper , you will likely have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and its scholarly context
• Develop a theoretical framework and methodology for your research
• Position your work in relation to other researchers and theorists
• Show how your research addresses a gap or contributes to a debate
• Evaluate the current state of research and demonstrate your knowledge of the scholarly debates around your topic.

Writing literature reviews is a particularly important skill if you want to apply for graduate school or pursue a career in research. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research problem and questions .

Make a list of keywords

Start by creating a list of keywords related to your research question. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list as you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some useful databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can also use boolean operators to help narrow down your search.

Make sure to read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

You likely won’t be able to read absolutely everything that has been written on your topic, so it will be necessary to evaluate which sources are most relevant to your research question.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models, and methods?
• Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible , and make sure you read any landmark studies and major theories in your field of research.

You can use our template to summarize and evaluate sources you’re thinking about using. Click on either button below to download.

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It is important to keep track of your sources with citations to avoid plagiarism . It can be helpful to make an annotated bibliography , where you compile full citation information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

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To begin organizing your literature review’s argument and structure, be sure you understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly visual platforms like Instagram and Snapchat—this is a gap that you could address in your own research.

There are various approaches to organizing the body of a literature review. Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarizing sources in order.

Try to analyze patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organize your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text , your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, you can follow these tips:

• Summarize and synthesize: give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: don’t just paraphrase other researchers — add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically evaluate: mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: use transition words and topic sentences to draw connections, comparisons and contrasts

In the conclusion, you should summarize the key findings you have taken from the literature and emphasize their significance.

When you’ve finished writing and revising your literature review, don’t forget to proofread thoroughly before submitting. Not a language expert? Check out Scribbr’s professional proofreading services !

This article has been adapted into lecture slides that you can use to teach your students about writing a literature review.

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If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

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• Likert scales
• Reproducibility

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• Null hypothesis
• Statistical power
• Probability distribution
• Effect size
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Research bias

• Optimism bias
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A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarize yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your thesis or dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

A literature review is a survey of credible sources on a topic, often used in dissertations , theses, and research papers . Literature reviews give an overview of knowledge on a subject, helping you identify relevant theories and methods, as well as gaps in existing research. Literature reviews are set up similarly to other  academic texts , with an introduction , a main body, and a conclusion .

An  annotated bibliography is a list of  source references that has a short description (called an annotation ) for each of the sources. It is often assigned as part of the research process for a  paper .  

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically Evaluate: Mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

A comparative review may, e.g., require you to examine two schools of thought, two issues, or the positions taken by two persons. You may create a hierarchy of issues and sub-issues to compare and contrast, as suggested by the following general plan.

This model lists 3 options for structuring the body of the review. In all cases, you are expected to deal with the similarities ( compare ) and then with the differences ( contrast ): Introduction, Body, & Conclusion

Literature Review Example 3 offers an excellent example of  a comparative review [ Language and gender ]. This was written by Alastair Pennycook for his undergraduate students as a model of (among other things) of how to structure a  review of the literature - for an example of the above structure.

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What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Discovers relationships between research studies/ideas.
• Identifies major themes, concepts, and researchers on a topic.
• Identifies critical gaps and points of disagreement.
• Discusses further research questions that logically come out of the previous studies.

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1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

• Make sure your research question is not too broad or too narrow.  Is it manageable?
• Begin writing down terms that are related to your question. These will be useful for searches later.
• If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

• This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

• use the tabs on this guide
• Find other databases in the Nursing Information Resources web page
• More on the Medical Library web page
• ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

• Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
• Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
• Review the abstracts of research studies carefully. This will save you time.
• Use the bibliographies and references of research studies you find to locate others.
• Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
• Ask your librarian for help at any time.
• Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

• What was the research question of the study you are reviewing? What were the authors trying to discover?
• Was the research funded by a source that could influence the findings?
• What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
• Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
• If there are conflicting studies, why do you think that is?
• How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

• Review the abstracts carefully.  
• Keep careful notes so that you may track your thought processes during the research process.
• Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
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Learn how to write a review of literature

What is a review of literature.

The format of a review of literature may vary from discipline to discipline and from assignment to assignment.

A review may be a self-contained unit — an end in itself — or a preface to and rationale for engaging in primary research. A review is a required part of grant and research proposals and often a chapter in theses and dissertations.

Generally, the purpose of a review is to analyze critically a segment of a published body of knowledge through summary, classification, and comparison of prior research studies, reviews of literature, and theoretical articles.

Writing the introduction

In the introduction, you should:

Define or identify the general topic, issue, or area of concern, thus providing an appropriate context for reviewing the literature.

Point out overall trends in what has been published about the topic; or conflicts in theory, methodology, evidence, and conclusions; or gaps in research and scholarship; or a single problem or new perspective of immediate interest.

Establish the writer’s reason (point of view) for reviewing the literature; explain the criteria to be used in analyzing and comparing literature and the organization of the review (sequence); and, when necessary, state why certain literature is or is not included (scope).

Writing the body

In the body, you should:

Group research studies and other types of literature (reviews, theoretical articles, case studies, etc.) according to common denominators such as qualitative versus quantitative approaches, conclusions of authors, specific purpose or objective, chronology, etc.

Summarize individual studies or articles with as much or as little detail as each merits according to its comparative importance in the literature, remembering that space (length) denotes significance.

Provide the reader with strong “umbrella” sentences at beginnings of paragraphs, “signposts” throughout, and brief “so what” summary sentences at intermediate points in the review to aid in understanding comparisons and analyses.

Writing the conclusion

In the conclusion, you should:

Summarize major contributions of significant studies and articles to the body of knowledge under review, maintaining the focus established in the introduction.

Evaluate the current “state of the art” for the body of knowledge reviewed, pointing out major methodological flaws or gaps in research, inconsistencies in theory and findings, and areas or issues pertinent to future study.

Conclude by providing some insight into the relationship between the central topic of the literature review and a larger area of study such as a discipline, a scientific endeavor, or a profession.

For further information see our handouts on Writing a Critical Review of a Nonfiction Book or Article or Reading a Book to Review It .

To learn more about literature reviews, take a look at our workshop on Writing Literature Reviews of Published Research.

Sample Literature Reviews

An important strategy for learning how to compose literature reviews in your field or within a specific genre is to locate and analyze representative examples. The following collection of annotated sample literature reviews written and co-written by colleagues associated with UW-Madison showcases how these reviews can do different kind of work for different purposes. Use these successful examples as a starting point for understanding how other writers have approached the challenging and important task of situating their idea in the context of established research.

• Sample 1 (PDF) A brief literature review within a political scientists’  National Science Foundation Graduate Research Fellowship  grant
• Sample 2 (PDF) A several-page literature review at the beginning of a published, academic article about philosophy
• Sample 3 (PDF) A brief literature review at the beginning of a published, academic article about photochemistry

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• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list if you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can use boolean operators to help narrow down your search:

Read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models and methods? Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible, and make sure you read any landmark studies and major theories in your field of research.

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

You can use our free APA Reference Generator for quick, correct, consistent citations.

Prevent plagiarism, run a free check.

To begin organising your literature review’s argument and structure, you need to understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly-visual platforms like Instagram and Snapchat – this is a gap that you could address in your own research.

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarising sources in order.

Try to analyse patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organise your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text, your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, discussing the significance of findings in relation to the literature as a whole.
• Critically evaluate: mention the strengths and weaknesses of your sources.
• Write in well-structured paragraphs: use transitions and topic sentences to draw connections, comparisons and contrasts.

In the conclusion, you should summarise the key findings you have taken from the literature and emphasise their significance.

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

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How to Write a Literature Review

What is a literature review.

• What Is the Literature
• Writing the Review

A literature review is much more than an annotated bibliography or a list of separate reviews of articles and books. It is a critical, analytical summary and synthesis of the current knowledge of a topic. Thus it should compare and relate different theories, findings, etc, rather than just summarize them individually. In addition, it should have a particular focus or theme to organize the review. It does not have to be an exhaustive account of everything published on the topic, but it should discuss all the significant academic literature and other relevant sources important for that focus.

This is meant to be a general guide to writing a literature review: ways to structure one, what to include, how it supplements other research. For more specific help on writing a review, and especially for help on finding the literature to review, sign up for a Personal Research Session .

The specific organization of a literature review depends on the type and purpose of the review, as well as on the specific field or topic being reviewed. But in general, it is a relatively brief but thorough exploration of past and current work on a topic. Rather than a chronological listing of previous work, though, literature reviews are usually organized thematically, such as different theoretical approaches, methodologies, or specific issues or concepts involved in the topic. A thematic organization makes it much easier to examine contrasting perspectives, theoretical approaches, methodologies, findings, etc, and to analyze the strengths and weaknesses of, and point out any gaps in, previous research. And this is the heart of what a literature review is about. A literature review may offer new interpretations, theoretical approaches, or other ideas; if it is part of a research proposal or report it should demonstrate the relationship of the proposed or reported research to others' work; but whatever else it does, it must provide a critical overview of the current state of research efforts. 

Literature reviews are common and very important in the sciences and social sciences. They are less common and have a less important role in the humanities, but they do have a place, especially stand-alone reviews.

Types of Literature Reviews

There are different types of literature reviews, and different purposes for writing a review, but the most common are:

• Stand-alone literature review articles . These provide an overview and analysis of the current state of research on a topic or question. The goal is to evaluate and compare previous research on a topic to provide an analysis of what is currently known, and also to reveal controversies, weaknesses, and gaps in current work, thus pointing to directions for future research. You can find examples published in any number of academic journals, but there is a series of Annual Reviews of *Subject* which are specifically devoted to literature review articles. Writing a stand-alone review is often an effective way to get a good handle on a topic and to develop ideas for your own research program. For example, contrasting theoretical approaches or conflicting interpretations of findings can be the basis of your research project: can you find evidence supporting one interpretation against another, or can you propose an alternative interpretation that overcomes their limitations?
• Part of a research proposal . This could be a proposal for a PhD dissertation, a senior thesis, or a class project. It could also be a submission for a grant. The literature review, by pointing out the current issues and questions concerning a topic, is a crucial part of demonstrating how your proposed research will contribute to the field, and thus of convincing your thesis committee to allow you to pursue the topic of your interest or a funding agency to pay for your research efforts.
• Part of a research report . When you finish your research and write your thesis or paper to present your findings, it should include a literature review to provide the context to which your work is a contribution. Your report, in addition to detailing the methods, results, etc. of your research, should show how your work relates to others' work.

A literature review for a research report is often a revision of the review for a research proposal, which can be a revision of a stand-alone review. Each revision should be a fairly extensive revision. With the increased knowledge of and experience in the topic as you proceed, your understanding of the topic will increase. Thus, you will be in a better position to analyze and critique the literature. In addition, your focus will change as you proceed in your research. Some areas of the literature you initially reviewed will be marginal or irrelevant for your eventual research, and you will need to explore other areas more thoroughly. 

Examples of Literature Reviews

See the series of Annual Reviews of *Subject* which are specifically devoted to literature review articles to find many examples of stand-alone literature reviews in the biomedical, physical, and social sciences. 

Research report articles vary in how they are organized, but a common general structure is to have sections such as:

• Abstract - Brief summary of the contents of the article
• Introduction - A explanation of the purpose of the study, a statement of the research question(s) the study intends to address
• Literature review - A critical assessment of the work done so far on this topic, to show how the current study relates to what has already been done
• Methods - How the study was carried out (e.g. instruments or equipment, procedures, methods to gather and analyze data)
• Results - What was found in the course of the study
• Discussion - What do the results mean
• Conclusion - State the conclusions and implications of the results, and discuss how it relates to the work reviewed in the literature review; also, point to directions for further work in the area

Here are some articles that illustrate variations on this theme. There is no need to read the entire articles (unless the contents interest you); just quickly browse through to see the sections, and see how each section is introduced and what is contained in them.

The Determinants of Undergraduate Grade Point Average: The Relative Importance of Family Background, High School Resources, and Peer Group Effects , in The Journal of Human Resources , v. 34 no. 2 (Spring 1999), p. 268-293.

This article has a standard breakdown of sections:

• Introduction
• Literature Review
• Some discussion sections

First Encounters of the Bureaucratic Kind: Early Freshman Experiences with a Campus Bureaucracy , in The Journal of Higher Education , v. 67 no. 6 (Nov-Dec 1996), p. 660-691.

This one does not have a section specifically labeled as a "literature review" or "review of the literature," but the first few sections cite a long list of other sources discussing previous research in the area before the authors present their own study they are reporting.

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• Last Updated: Jan 11, 2024 9:48 AM
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Instructor Resources

Comparative essay.

Compare two or more literary works that we have studied in this class. Your comparative essay should not only compare but also contrast the literary texts, addressing the similarities and differences found within the texts.

Step 1: Identify the Basis for Comparison

Identify the basis of comparison. In other words, what aspect of the literature will you compare? (Theme, tone, point of view, setting, language, etc.)

Step 2: Create a List of Similarities and Differences

Carefully examine the literary texts for similarities and difference using the criteria you identified in step 1.

Step 3: Write a Thesis Statement

A thesis statement is the author’s educated opinion that can be defended. For a comparative essay, your thesis statement should assert why the similarities and differences between the literary works matter.

Step 4: Create a Structure

Before drafting, create an outline. Your introduction should draw the reader in and provide the thesis statement. The supporting paragraphs should begin with a topic sentence that supports your thesis statement; each topic sentence should then be supported with textual evidence. The conclusion should summarize the essay and prompt the reader to continue thinking about the topic.

Word Count: approximately 1500 words

Outside Sources needed: none (but use plenty of textual evidence)

• Comparative Essay. License : CC0: No Rights Reserved

Libraries | Research Guides

Literature reviews, what is a literature review, learning more about how to do a literature review.

• Planning the Review
• The Research Question
• Choosing Where to Search
• Organizing the Review
• Writing the Review

A literature review is a review and synthesis of existing research on a topic or research question. A literature review is meant to analyze the scholarly literature, make connections across writings and identify strengths, weaknesses, trends, and missing conversations. A literature review should address different aspects of a topic as it relates to your research question. A literature review goes beyond a description or summary of the literature you have read. 

• Sage Research Methods Core Collection This link opens in a new window SAGE Research Methods supports research at all levels by providing material to guide users through every step of the research process. SAGE Research Methods is the ultimate methods library with more than 1000 books, reference works, journal articles, and instructional videos by world-leading academics from across the social sciences, including the largest collection of qualitative methods books available online from any scholarly publisher. – Publisher

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• UConn Library
• Literature Review: The What, Why and How-to Guide
• Introduction

Literature Review: The What, Why and How-to Guide — Introduction

• Getting Started
• How to Pick a Topic
• Strategies to Find Sources
• Evaluating Sources & Lit. Reviews
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings

What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D.  The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review?  A literature could be written to accomplish different aims:

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews .  Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

• A research paper assigned in a course
• A thesis or dissertation
• A grant proposal
• An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

• Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework:  10.1177/08948453211037398  

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

• Example : The effect of leave policies on increasing fertility: a systematic review:  10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

• Example : Employment Instability and Fertility in Europe: A Meta-Analysis:  10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts .  Journal of Advanced Nursing , 53 (3), 311-318.

• Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis:  10.1177/05390184221113735

Literature Reviews in the Health Sciences

• UConn Health subject guide on systematic reviews Explanation of the different review types used in health sciences literature as well as tools to help you find the right review type
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Literature Reviews

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What is a literature review?

A literature review discusses published information in a particular subject area. Often part of the introduction to an essay, research report or thesis, the literature review is literally a "re" view or "look again" at what has already been written about the topic, wherein the author analyzes a segment of a published body of knowledge through summary, classification, and comparison of prior research studies, reviews of literature, and theoretical articles. Literature reviews provide the reader with a bibliographic history of the scholarly research in any given field of study. As such,  as new information becomes available, literature reviews grow in length or become focused on one specific aspect of the topic.

A literature review can be just a simple summary of the sources, but usually contains an organizational pattern and combines both summary and synthesis. A summary is a recap of the important information of the source, whereas a synthesis is a re-organization, or a reshuffling, of that information. The literature review might give a new interpretation of old material or combine new with old interpretations. Or it might trace the intellectual progression of the field, including major debates. Depending on the situation, the literature review may evaluate the sources and advise the reader on the most pertinent or relevant.

A literature review is NOT:

• An annotated bibliography – a list of citations to books, articles and documents that includes a brief description and evaluation for each citation. The annotations inform the reader of the relevance, accuracy and quality of the sources cited.
• A literary review – a critical discussion of the merits and weaknesses of a literary work.
• A book review – a critical discussion of the merits and weaknesses of a particular book.
• Teaching Information Literacy Reframed: 50+ Framework-Based Exercises for Creating Information-Literate Learners
• The UNC Writing Center – Literature Reviews
• The UW-Madison Writing Center: The Writer’s Handbook – Academic and Professional Writing – Learn How to Write a Literature Review

What is the difference between a literature review and a research paper?

The focus of a literature review is to summarize and synthesize the arguments and ideas of others without adding new contributions, whereas academic research papers present and develop new arguments that build upon the previously available body of literature.

How do I write a literature review?

There are many resources that offer step-by-step guidance for writing a literature review, and you can find some of them under Other Resources in the menu to the left. Writing the Literature Review: A Practical Guide suggests these steps:

• Chose a review topic and develop a research question
• Locate and organize research sources
• Select, analyze and annotate sources
• Evaluate research articles and other documents
• Structure and organize the literature review
• Develop arguments and supporting claims
• Synthesize and interpret the literature
• Put it all together

What is the purpose of writing a literature review?

Literature reviews serve as a guide to a particular topic: professionals can use literature reviews to keep current on their field; scholars can determine credibility of the writer in his or her field by analyzing the literature review.

As a writer, you will use the literature review to:

• See what has, and what has not, been investigated about your topic
• Identify data sources that other researches have used
• Learn how others in the field have defined and measured key concepts
• Establish context, or background, for the argument explored in the rest of a paper
• Explain what the strengths and weaknesses of that knowledge and ideas might be
• Contribute to the field by moving research forward
• To keep the writer/reader up to date with current developments in a particular field of study
• Develop alternative research projects
• Put your work in perspective
• Demonstrate your understanding and your ability to critically evaluate research in the field
• Provide evidence that may support your own findings
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Literature Reviews

• Getting started

What is a literature review?

Why conduct a literature review, stages of a literature review, lit reviews: an overview (video), check out these books.

• Types of reviews
• 1. Define your research question
• 2. Plan your search
• 3. Search the literature
• 4. Organize your results
• 5. Synthesize your findings
• 6. Write the review
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Definition: A literature review is a systematic examination and synthesis of existing scholarly research on a specific topic or subject.

Purpose: It serves to provide a comprehensive overview of the current state of knowledge within a particular field.

Analysis: Involves critically evaluating and summarizing key findings, methodologies, and debates found in academic literature.

Identifying Gaps: Aims to pinpoint areas where there is a lack of research or unresolved questions, highlighting opportunities for further investigation.

Contextualization: Enables researchers to understand how their work fits into the broader academic conversation and contributes to the existing body of knowledge.

tl;dr  A literature review critically examines and synthesizes existing scholarly research and publications on a specific topic to provide a comprehensive understanding of the current state of knowledge in the field.

What is a literature review NOT?

❌ An annotated bibliography

❌ Original research

❌ A summary

❌ Something to be conducted at the end of your research

❌ An opinion piece

❌ A chronological compilation of studies

The reason for conducting a literature review is to:

Literature Reviews: An Overview for Graduate Students

While this 9-minute video from NCSU is geared toward graduate students, it is useful for anyone conducting a literature review.

Writing the literature review: A practical guide

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Writing literature reviews: A guide for students of the social and behavioral sciences

Available online!

So, you have to write a literature review: A guided workbook for engineers

Telling a research story: Writing a literature review

The literature review: Six steps to success

Systematic approaches to a successful literature review

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Doing a systematic review: A student's guide

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Which review is that? A guide to review types.

• Which review is that?

Review Comparison Chart

• Decision Tool
• Critical Review
• Integrative Review
• Narrative Review
• State of the Art Review
• Narrative Summary
• Systematic Review
• Meta-analysis
• Comparative Effectiveness Review
• Diagnostic Systematic Review
• Network Meta-analysis
• Prognostic Review
• Psychometric Review
• Review of Economic Evaluations
• Systematic Review of Epidemiology Studies
• Living Systematic Reviews
• Umbrella Review
• Review of Reviews
• Rapid Review
• Rapid Evidence Assessment
• Rapid Realist Review
• Qualitative Evidence Synthesis
• Qualitative Interpretive Meta-synthesis
• Qualitative Meta-synthesis
• Qualitative Research Synthesis
• Framework Synthesis - Best-fit Framework Synthesis
• Meta-aggregation
• Meta-ethnography
• Meta-interpretation
• Meta-narrative Review
• Meta-summary
• Thematic Synthesis
• Mixed Methods Synthesis
• Narrative Synthesis
• Bayesian Meta-analysis
• EPPI-Centre Review
• Critical Interpretive Synthesis
• Realist Synthesis - Realist Review
• Scoping Review
• Mapping Review
• Systematised Review
• Concept Synthesis
• Expert Opinion - Policy Review
• Technology Assessment Review
• Methodological Review
• Systematic Search and Review

A selection of the common review types found in the literature is presented and compared in the following table using the SALSA framework developed by Grant and Booth (2009).

Adapted from:

Grant, M.J. and Booth, A. (2009), A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26: 91-108.  https://doi.org/10.1111/j.1471-1842.2009.00848.x

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Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
• Choose databases and search
• Review Results
• Synthesize Results
• Analyze Results
• Librarian Support

What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
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Lau F, Kuziemsky C, editors. Handbook of eHealth Evaluation: An Evidence-based Approach [Internet]. Victoria (BC): University of Victoria; 2017 Feb 27.

Handbook of eHealth Evaluation: An Evidence-based Approach [Internet].

Chapter 9 methods for literature reviews.

Guy Paré and Spyros Kitsiou .

9.1. Introduction

Literature reviews play a critical role in scholarship because science remains, first and foremost, a cumulative endeavour ( vom Brocke et al., 2009 ). As in any academic discipline, rigorous knowledge syntheses are becoming indispensable in keeping up with an exponentially growing eHealth literature, assisting practitioners, academics, and graduate students in finding, evaluating, and synthesizing the contents of many empirical and conceptual papers. Among other methods, literature reviews are essential for: (a) identifying what has been written on a subject or topic; (b) determining the extent to which a specific research area reveals any interpretable trends or patterns; (c) aggregating empirical findings related to a narrow research question to support evidence-based practice; (d) generating new frameworks and theories; and (e) identifying topics or questions requiring more investigation ( Paré, Trudel, Jaana, & Kitsiou, 2015 ).

Literature reviews can take two major forms. The most prevalent one is the “literature review” or “background” section within a journal paper or a chapter in a graduate thesis. This section synthesizes the extant literature and usually identifies the gaps in knowledge that the empirical study addresses ( Sylvester, Tate, & Johnstone, 2013 ). It may also provide a theoretical foundation for the proposed study, substantiate the presence of the research problem, justify the research as one that contributes something new to the cumulated knowledge, or validate the methods and approaches for the proposed study ( Hart, 1998 ; Levy & Ellis, 2006 ).

The second form of literature review, which is the focus of this chapter, constitutes an original and valuable work of research in and of itself ( Paré et al., 2015 ). Rather than providing a base for a researcher’s own work, it creates a solid starting point for all members of the community interested in a particular area or topic ( Mulrow, 1987 ). The so-called “review article” is a journal-length paper which has an overarching purpose to synthesize the literature in a field, without collecting or analyzing any primary data ( Green, Johnson, & Adams, 2006 ).

When appropriately conducted, review articles represent powerful information sources for practitioners looking for state-of-the art evidence to guide their decision-making and work practices ( Paré et al., 2015 ). Further, high-quality reviews become frequently cited pieces of work which researchers seek out as a first clear outline of the literature when undertaking empirical studies ( Cooper, 1988 ; Rowe, 2014 ). Scholars who track and gauge the impact of articles have found that review papers are cited and downloaded more often than any other type of published article ( Cronin, Ryan, & Coughlan, 2008 ; Montori, Wilczynski, Morgan, Haynes, & Hedges, 2003 ; Patsopoulos, Analatos, & Ioannidis, 2005 ). The reason for their popularity may be the fact that reading the review enables one to have an overview, if not a detailed knowledge of the area in question, as well as references to the most useful primary sources ( Cronin et al., 2008 ). Although they are not easy to conduct, the commitment to complete a review article provides a tremendous service to one’s academic community ( Paré et al., 2015 ; Petticrew & Roberts, 2006 ). Most, if not all, peer-reviewed journals in the fields of medical informatics publish review articles of some type.

The main objectives of this chapter are fourfold: (a) to provide an overview of the major steps and activities involved in conducting a stand-alone literature review; (b) to describe and contrast the different types of review articles that can contribute to the eHealth knowledge base; (c) to illustrate each review type with one or two examples from the eHealth literature; and (d) to provide a series of recommendations for prospective authors of review articles in this domain.

9.2. Overview of the Literature Review Process and Steps

As explained in Templier and Paré (2015) , there are six generic steps involved in conducting a review article:

• formulating the research question(s) and objective(s),
• searching the extant literature,
• screening for inclusion,
• assessing the quality of primary studies,
• extracting data, and
• analyzing data.

Although these steps are presented here in sequential order, one must keep in mind that the review process can be iterative and that many activities can be initiated during the planning stage and later refined during subsequent phases ( Finfgeld-Connett & Johnson, 2013 ; Kitchenham & Charters, 2007 ).

Formulating the research question(s) and objective(s): As a first step, members of the review team must appropriately justify the need for the review itself ( Petticrew & Roberts, 2006 ), identify the review’s main objective(s) ( Okoli & Schabram, 2010 ), and define the concepts or variables at the heart of their synthesis ( Cooper & Hedges, 2009 ; Webster & Watson, 2002 ). Importantly, they also need to articulate the research question(s) they propose to investigate ( Kitchenham & Charters, 2007 ). In this regard, we concur with Jesson, Matheson, and Lacey (2011) that clearly articulated research questions are key ingredients that guide the entire review methodology; they underscore the type of information that is needed, inform the search for and selection of relevant literature, and guide or orient the subsequent analysis. Searching the extant literature: The next step consists of searching the literature and making decisions about the suitability of material to be considered in the review ( Cooper, 1988 ). There exist three main coverage strategies. First, exhaustive coverage means an effort is made to be as comprehensive as possible in order to ensure that all relevant studies, published and unpublished, are included in the review and, thus, conclusions are based on this all-inclusive knowledge base. The second type of coverage consists of presenting materials that are representative of most other works in a given field or area. Often authors who adopt this strategy will search for relevant articles in a small number of top-tier journals in a field ( Paré et al., 2015 ). In the third strategy, the review team concentrates on prior works that have been central or pivotal to a particular topic. This may include empirical studies or conceptual papers that initiated a line of investigation, changed how problems or questions were framed, introduced new methods or concepts, or engendered important debate ( Cooper, 1988 ). Screening for inclusion: The following step consists of evaluating the applicability of the material identified in the preceding step ( Levy & Ellis, 2006 ; vom Brocke et al., 2009 ). Once a group of potential studies has been identified, members of the review team must screen them to determine their relevance ( Petticrew & Roberts, 2006 ). A set of predetermined rules provides a basis for including or excluding certain studies. This exercise requires a significant investment on the part of researchers, who must ensure enhanced objectivity and avoid biases or mistakes. As discussed later in this chapter, for certain types of reviews there must be at least two independent reviewers involved in the screening process and a procedure to resolve disagreements must also be in place ( Liberati et al., 2009 ; Shea et al., 2009 ). Assessing the quality of primary studies: In addition to screening material for inclusion, members of the review team may need to assess the scientific quality of the selected studies, that is, appraise the rigour of the research design and methods. Such formal assessment, which is usually conducted independently by at least two coders, helps members of the review team refine which studies to include in the final sample, determine whether or not the differences in quality may affect their conclusions, or guide how they analyze the data and interpret the findings ( Petticrew & Roberts, 2006 ). Ascribing quality scores to each primary study or considering through domain-based evaluations which study components have or have not been designed and executed appropriately makes it possible to reflect on the extent to which the selected study addresses possible biases and maximizes validity ( Shea et al., 2009 ). Extracting data: The following step involves gathering or extracting applicable information from each primary study included in the sample and deciding what is relevant to the problem of interest ( Cooper & Hedges, 2009 ). Indeed, the type of data that should be recorded mainly depends on the initial research questions ( Okoli & Schabram, 2010 ). However, important information may also be gathered about how, when, where and by whom the primary study was conducted, the research design and methods, or qualitative/quantitative results ( Cooper & Hedges, 2009 ). Analyzing and synthesizing data : As a final step, members of the review team must collate, summarize, aggregate, organize, and compare the evidence extracted from the included studies. The extracted data must be presented in a meaningful way that suggests a new contribution to the extant literature ( Jesson et al., 2011 ). Webster and Watson (2002) warn researchers that literature reviews should be much more than lists of papers and should provide a coherent lens to make sense of extant knowledge on a given topic. There exist several methods and techniques for synthesizing quantitative (e.g., frequency analysis, meta-analysis) and qualitative (e.g., grounded theory, narrative analysis, meta-ethnography) evidence ( Dixon-Woods, Agarwal, Jones, Young, & Sutton, 2005 ; Thomas & Harden, 2008 ).

9.3. Types of Review Articles and Brief Illustrations

EHealth researchers have at their disposal a number of approaches and methods for making sense out of existing literature, all with the purpose of casting current research findings into historical contexts or explaining contradictions that might exist among a set of primary research studies conducted on a particular topic. Our classification scheme is largely inspired from Paré and colleagues’ (2015) typology. Below we present and illustrate those review types that we feel are central to the growth and development of the eHealth domain.

9.3.1. Narrative Reviews

The narrative review is the “traditional” way of reviewing the extant literature and is skewed towards a qualitative interpretation of prior knowledge ( Sylvester et al., 2013 ). Put simply, a narrative review attempts to summarize or synthesize what has been written on a particular topic but does not seek generalization or cumulative knowledge from what is reviewed ( Davies, 2000 ; Green et al., 2006 ). Instead, the review team often undertakes the task of accumulating and synthesizing the literature to demonstrate the value of a particular point of view ( Baumeister & Leary, 1997 ). As such, reviewers may selectively ignore or limit the attention paid to certain studies in order to make a point. In this rather unsystematic approach, the selection of information from primary articles is subjective, lacks explicit criteria for inclusion and can lead to biased interpretations or inferences ( Green et al., 2006 ). There are several narrative reviews in the particular eHealth domain, as in all fields, which follow such an unstructured approach ( Silva et al., 2015 ; Paul et al., 2015 ).

Despite these criticisms, this type of review can be very useful in gathering together a volume of literature in a specific subject area and synthesizing it. As mentioned above, its primary purpose is to provide the reader with a comprehensive background for understanding current knowledge and highlighting the significance of new research ( Cronin et al., 2008 ). Faculty like to use narrative reviews in the classroom because they are often more up to date than textbooks, provide a single source for students to reference, and expose students to peer-reviewed literature ( Green et al., 2006 ). For researchers, narrative reviews can inspire research ideas by identifying gaps or inconsistencies in a body of knowledge, thus helping researchers to determine research questions or formulate hypotheses. Importantly, narrative reviews can also be used as educational articles to bring practitioners up to date with certain topics of issues ( Green et al., 2006 ).

Recently, there have been several efforts to introduce more rigour in narrative reviews that will elucidate common pitfalls and bring changes into their publication standards. Information systems researchers, among others, have contributed to advancing knowledge on how to structure a “traditional” review. For instance, Levy and Ellis (2006) proposed a generic framework for conducting such reviews. Their model follows the systematic data processing approach comprised of three steps, namely: (a) literature search and screening; (b) data extraction and analysis; and (c) writing the literature review. They provide detailed and very helpful instructions on how to conduct each step of the review process. As another methodological contribution, vom Brocke et al. (2009) offered a series of guidelines for conducting literature reviews, with a particular focus on how to search and extract the relevant body of knowledge. Last, Bandara, Miskon, and Fielt (2011) proposed a structured, predefined and tool-supported method to identify primary studies within a feasible scope, extract relevant content from identified articles, synthesize and analyze the findings, and effectively write and present the results of the literature review. We highly recommend that prospective authors of narrative reviews consult these useful sources before embarking on their work.

Darlow and Wen (2015) provide a good example of a highly structured narrative review in the eHealth field. These authors synthesized published articles that describe the development process of mobile health ( m-health ) interventions for patients’ cancer care self-management. As in most narrative reviews, the scope of the research questions being investigated is broad: (a) how development of these systems are carried out; (b) which methods are used to investigate these systems; and (c) what conclusions can be drawn as a result of the development of these systems. To provide clear answers to these questions, a literature search was conducted on six electronic databases and Google Scholar . The search was performed using several terms and free text words, combining them in an appropriate manner. Four inclusion and three exclusion criteria were utilized during the screening process. Both authors independently reviewed each of the identified articles to determine eligibility and extract study information. A flow diagram shows the number of studies identified, screened, and included or excluded at each stage of study selection. In terms of contributions, this review provides a series of practical recommendations for m-health intervention development.

9.3.2. Descriptive or Mapping Reviews

The primary goal of a descriptive review is to determine the extent to which a body of knowledge in a particular research topic reveals any interpretable pattern or trend with respect to pre-existing propositions, theories, methodologies or findings ( King & He, 2005 ; Paré et al., 2015 ). In contrast with narrative reviews, descriptive reviews follow a systematic and transparent procedure, including searching, screening and classifying studies ( Petersen, Vakkalanka, & Kuzniarz, 2015 ). Indeed, structured search methods are used to form a representative sample of a larger group of published works ( Paré et al., 2015 ). Further, authors of descriptive reviews extract from each study certain characteristics of interest, such as publication year, research methods, data collection techniques, and direction or strength of research outcomes (e.g., positive, negative, or non-significant) in the form of frequency analysis to produce quantitative results ( Sylvester et al., 2013 ). In essence, each study included in a descriptive review is treated as the unit of analysis and the published literature as a whole provides a database from which the authors attempt to identify any interpretable trends or draw overall conclusions about the merits of existing conceptualizations, propositions, methods or findings ( Paré et al., 2015 ). In doing so, a descriptive review may claim that its findings represent the state of the art in a particular domain ( King & He, 2005 ).

In the fields of health sciences and medical informatics, reviews that focus on examining the range, nature and evolution of a topic area are described by Anderson, Allen, Peckham, and Goodwin (2008) as mapping reviews . Like descriptive reviews, the research questions are generic and usually relate to publication patterns and trends. There is no preconceived plan to systematically review all of the literature although this can be done. Instead, researchers often present studies that are representative of most works published in a particular area and they consider a specific time frame to be mapped.

An example of this approach in the eHealth domain is offered by DeShazo, Lavallie, and Wolf (2009). The purpose of this descriptive or mapping review was to characterize publication trends in the medical informatics literature over a 20-year period (1987 to 2006). To achieve this ambitious objective, the authors performed a bibliometric analysis of medical informatics citations indexed in medline using publication trends, journal frequencies, impact factors, Medical Subject Headings (MeSH) term frequencies, and characteristics of citations. Findings revealed that there were over 77,000 medical informatics articles published during the covered period in numerous journals and that the average annual growth rate was 12%. The MeSH term analysis also suggested a strong interdisciplinary trend. Finally, average impact scores increased over time with two notable growth periods. Overall, patterns in research outputs that seem to characterize the historic trends and current components of the field of medical informatics suggest it may be a maturing discipline (DeShazo et al., 2009).

9.3.3. Scoping Reviews

Scoping reviews attempt to provide an initial indication of the potential size and nature of the extant literature on an emergent topic (Arksey & O’Malley, 2005; Daudt, van Mossel, & Scott, 2013 ; Levac, Colquhoun, & O’Brien, 2010). A scoping review may be conducted to examine the extent, range and nature of research activities in a particular area, determine the value of undertaking a full systematic review (discussed next), or identify research gaps in the extant literature ( Paré et al., 2015 ). In line with their main objective, scoping reviews usually conclude with the presentation of a detailed research agenda for future works along with potential implications for both practice and research.

Unlike narrative and descriptive reviews, the whole point of scoping the field is to be as comprehensive as possible, including grey literature (Arksey & O’Malley, 2005). Inclusion and exclusion criteria must be established to help researchers eliminate studies that are not aligned with the research questions. It is also recommended that at least two independent coders review abstracts yielded from the search strategy and then the full articles for study selection ( Daudt et al., 2013 ). The synthesized evidence from content or thematic analysis is relatively easy to present in tabular form (Arksey & O’Malley, 2005; Thomas & Harden, 2008 ).

One of the most highly cited scoping reviews in the eHealth domain was published by Archer, Fevrier-Thomas, Lokker, McKibbon, and Straus (2011) . These authors reviewed the existing literature on personal health record ( phr ) systems including design, functionality, implementation, applications, outcomes, and benefits. Seven databases were searched from 1985 to March 2010. Several search terms relating to phr s were used during this process. Two authors independently screened titles and abstracts to determine inclusion status. A second screen of full-text articles, again by two independent members of the research team, ensured that the studies described phr s. All in all, 130 articles met the criteria and their data were extracted manually into a database. The authors concluded that although there is a large amount of survey, observational, cohort/panel, and anecdotal evidence of phr benefits and satisfaction for patients, more research is needed to evaluate the results of phr implementations. Their in-depth analysis of the literature signalled that there is little solid evidence from randomized controlled trials or other studies through the use of phr s. Hence, they suggested that more research is needed that addresses the current lack of understanding of optimal functionality and usability of these systems, and how they can play a beneficial role in supporting patient self-management ( Archer et al., 2011 ).

9.3.4. Forms of Aggregative Reviews

Healthcare providers, practitioners, and policy-makers are nowadays overwhelmed with large volumes of information, including research-based evidence from numerous clinical trials and evaluation studies, assessing the effectiveness of health information technologies and interventions ( Ammenwerth & de Keizer, 2004 ; Deshazo et al., 2009 ). It is unrealistic to expect that all these disparate actors will have the time, skills, and necessary resources to identify the available evidence in the area of their expertise and consider it when making decisions. Systematic reviews that involve the rigorous application of scientific strategies aimed at limiting subjectivity and bias (i.e., systematic and random errors) can respond to this challenge.

Systematic reviews attempt to aggregate, appraise, and synthesize in a single source all empirical evidence that meet a set of previously specified eligibility criteria in order to answer a clearly formulated and often narrow research question on a particular topic of interest to support evidence-based practice ( Liberati et al., 2009 ). They adhere closely to explicit scientific principles ( Liberati et al., 2009 ) and rigorous methodological guidelines (Higgins & Green, 2008) aimed at reducing random and systematic errors that can lead to deviations from the truth in results or inferences. The use of explicit methods allows systematic reviews to aggregate a large body of research evidence, assess whether effects or relationships are in the same direction and of the same general magnitude, explain possible inconsistencies between study results, and determine the strength of the overall evidence for every outcome of interest based on the quality of included studies and the general consistency among them ( Cook, Mulrow, & Haynes, 1997 ). The main procedures of a systematic review involve:

• Formulating a review question and developing a search strategy based on explicit inclusion criteria for the identification of eligible studies (usually described in the context of a detailed review protocol).
• Searching for eligible studies using multiple databases and information sources, including grey literature sources, without any language restrictions.
• Selecting studies, extracting data, and assessing risk of bias in a duplicate manner using two independent reviewers to avoid random or systematic errors in the process.
• Analyzing data using quantitative or qualitative methods.
• Presenting results in summary of findings tables.
• Interpreting results and drawing conclusions.

Many systematic reviews, but not all, use statistical methods to combine the results of independent studies into a single quantitative estimate or summary effect size. Known as meta-analyses , these reviews use specific data extraction and statistical techniques (e.g., network, frequentist, or Bayesian meta-analyses) to calculate from each study by outcome of interest an effect size along with a confidence interval that reflects the degree of uncertainty behind the point estimate of effect ( Borenstein, Hedges, Higgins, & Rothstein, 2009 ; Deeks, Higgins, & Altman, 2008 ). Subsequently, they use fixed or random-effects analysis models to combine the results of the included studies, assess statistical heterogeneity, and calculate a weighted average of the effect estimates from the different studies, taking into account their sample sizes. The summary effect size is a value that reflects the average magnitude of the intervention effect for a particular outcome of interest or, more generally, the strength of a relationship between two variables across all studies included in the systematic review. By statistically combining data from multiple studies, meta-analyses can create more precise and reliable estimates of intervention effects than those derived from individual studies alone, when these are examined independently as discrete sources of information.

The review by Gurol-Urganci, de Jongh, Vodopivec-Jamsek, Atun, and Car (2013) on the effects of mobile phone messaging reminders for attendance at healthcare appointments is an illustrative example of a high-quality systematic review with meta-analysis. Missed appointments are a major cause of inefficiency in healthcare delivery with substantial monetary costs to health systems. These authors sought to assess whether mobile phone-based appointment reminders delivered through Short Message Service ( sms ) or Multimedia Messaging Service ( mms ) are effective in improving rates of patient attendance and reducing overall costs. To this end, they conducted a comprehensive search on multiple databases using highly sensitive search strategies without language or publication-type restrictions to identify all rct s that are eligible for inclusion. In order to minimize the risk of omitting eligible studies not captured by the original search, they supplemented all electronic searches with manual screening of trial registers and references contained in the included studies. Study selection, data extraction, and risk of bias assessments were performed inde­­pen­dently by two coders using standardized methods to ensure consistency and to eliminate potential errors. Findings from eight rct s involving 6,615 participants were pooled into meta-analyses to calculate the magnitude of effects that mobile text message reminders have on the rate of attendance at healthcare appointments compared to no reminders and phone call reminders.

Meta-analyses are regarded as powerful tools for deriving meaningful conclusions. However, there are situations in which it is neither reasonable nor appropriate to pool studies together using meta-analytic methods simply because there is extensive clinical heterogeneity between the included studies or variation in measurement tools, comparisons, or outcomes of interest. In these cases, systematic reviews can use qualitative synthesis methods such as vote counting, content analysis, classification schemes and tabulations, as an alternative approach to narratively synthesize the results of the independent studies included in the review. This form of review is known as qualitative systematic review.

A rigorous example of one such review in the eHealth domain is presented by Mickan, Atherton, Roberts, Heneghan, and Tilson (2014) on the use of handheld computers by healthcare professionals and their impact on access to information and clinical decision-making. In line with the methodological guide­lines for systematic reviews, these authors: (a) developed and registered with prospero ( www.crd.york.ac.uk/ prospero / ) an a priori review protocol; (b) conducted comprehensive searches for eligible studies using multiple databases and other supplementary strategies (e.g., forward searches); and (c) subsequently carried out study selection, data extraction, and risk of bias assessments in a duplicate manner to eliminate potential errors in the review process. Heterogeneity between the included studies in terms of reported outcomes and measures precluded the use of meta-analytic methods. To this end, the authors resorted to using narrative analysis and synthesis to describe the effectiveness of handheld computers on accessing information for clinical knowledge, adherence to safety and clinical quality guidelines, and diagnostic decision-making.

In recent years, the number of systematic reviews in the field of health informatics has increased considerably. Systematic reviews with discordant findings can cause great confusion and make it difficult for decision-makers to interpret the review-level evidence ( Moher, 2013 ). Therefore, there is a growing need for appraisal and synthesis of prior systematic reviews to ensure that decision-making is constantly informed by the best available accumulated evidence. Umbrella reviews , also known as overviews of systematic reviews, are tertiary types of evidence synthesis that aim to accomplish this; that is, they aim to compare and contrast findings from multiple systematic reviews and meta-analyses ( Becker & Oxman, 2008 ). Umbrella reviews generally adhere to the same principles and rigorous methodological guidelines used in systematic reviews. However, the unit of analysis in umbrella reviews is the systematic review rather than the primary study ( Becker & Oxman, 2008 ). Unlike systematic reviews that have a narrow focus of inquiry, umbrella reviews focus on broader research topics for which there are several potential interventions ( Smith, Devane, Begley, & Clarke, 2011 ). A recent umbrella review on the effects of home telemonitoring interventions for patients with heart failure critically appraised, compared, and synthesized evidence from 15 systematic reviews to investigate which types of home telemonitoring technologies and forms of interventions are more effective in reducing mortality and hospital admissions ( Kitsiou, Paré, & Jaana, 2015 ).

9.3.5. Realist Reviews

Realist reviews are theory-driven interpretative reviews developed to inform, enhance, or supplement conventional systematic reviews by making sense of heterogeneous evidence about complex interventions applied in diverse contexts in a way that informs policy decision-making ( Greenhalgh, Wong, Westhorp, & Pawson, 2011 ). They originated from criticisms of positivist systematic reviews which centre on their “simplistic” underlying assumptions ( Oates, 2011 ). As explained above, systematic reviews seek to identify causation. Such logic is appropriate for fields like medicine and education where findings of randomized controlled trials can be aggregated to see whether a new treatment or intervention does improve outcomes. However, many argue that it is not possible to establish such direct causal links between interventions and outcomes in fields such as social policy, management, and information systems where for any intervention there is unlikely to be a regular or consistent outcome ( Oates, 2011 ; Pawson, 2006 ; Rousseau, Manning, & Denyer, 2008 ).

To circumvent these limitations, Pawson, Greenhalgh, Harvey, and Walshe (2005) have proposed a new approach for synthesizing knowledge that seeks to unpack the mechanism of how “complex interventions” work in particular contexts. The basic research question — what works? — which is usually associated with systematic reviews changes to: what is it about this intervention that works, for whom, in what circumstances, in what respects and why? Realist reviews have no particular preference for either quantitative or qualitative evidence. As a theory-building approach, a realist review usually starts by articulating likely underlying mechanisms and then scrutinizes available evidence to find out whether and where these mechanisms are applicable ( Shepperd et al., 2009 ). Primary studies found in the extant literature are viewed as case studies which can test and modify the initial theories ( Rousseau et al., 2008 ).

The main objective pursued in the realist review conducted by Otte-Trojel, de Bont, Rundall, and van de Klundert (2014) was to examine how patient portals contribute to health service delivery and patient outcomes. The specific goals were to investigate how outcomes are produced and, most importantly, how variations in outcomes can be explained. The research team started with an exploratory review of background documents and research studies to identify ways in which patient portals may contribute to health service delivery and patient outcomes. The authors identified six main ways which represent “educated guesses” to be tested against the data in the evaluation studies. These studies were identified through a formal and systematic search in four databases between 2003 and 2013. Two members of the research team selected the articles using a pre-established list of inclusion and exclusion criteria and following a two-step procedure. The authors then extracted data from the selected articles and created several tables, one for each outcome category. They organized information to bring forward those mechanisms where patient portals contribute to outcomes and the variation in outcomes across different contexts.

9.3.6. Critical Reviews

Lastly, critical reviews aim to provide a critical evaluation and interpretive analysis of existing literature on a particular topic of interest to reveal strengths, weaknesses, contradictions, controversies, inconsistencies, and/or other important issues with respect to theories, hypotheses, research methods or results ( Baumeister & Leary, 1997 ; Kirkevold, 1997 ). Unlike other review types, critical reviews attempt to take a reflective account of the research that has been done in a particular area of interest, and assess its credibility by using appraisal instruments or critical interpretive methods. In this way, critical reviews attempt to constructively inform other scholars about the weaknesses of prior research and strengthen knowledge development by giving focus and direction to studies for further improvement ( Kirkevold, 1997 ).

Kitsiou, Paré, and Jaana (2013) provide an example of a critical review that assessed the methodological quality of prior systematic reviews of home telemonitoring studies for chronic patients. The authors conducted a comprehensive search on multiple databases to identify eligible reviews and subsequently used a validated instrument to conduct an in-depth quality appraisal. Results indicate that the majority of systematic reviews in this particular area suffer from important methodological flaws and biases that impair their internal validity and limit their usefulness for clinical and decision-making purposes. To this end, they provide a number of recommendations to strengthen knowledge development towards improving the design and execution of future reviews on home telemonitoring.

9.4. Summary

Table 9.1 outlines the main types of literature reviews that were described in the previous sub-sections and summarizes the main characteristics that distinguish one review type from another. It also includes key references to methodological guidelines and useful sources that can be used by eHealth scholars and researchers for planning and developing reviews.

Typology of Literature Reviews (adapted from Paré et al., 2015).

As shown in Table 9.1 , each review type addresses different kinds of research questions or objectives, which subsequently define and dictate the methods and approaches that need to be used to achieve the overarching goal(s) of the review. For example, in the case of narrative reviews, there is greater flexibility in searching and synthesizing articles ( Green et al., 2006 ). Researchers are often relatively free to use a diversity of approaches to search, identify, and select relevant scientific articles, describe their operational characteristics, present how the individual studies fit together, and formulate conclusions. On the other hand, systematic reviews are characterized by their high level of systematicity, rigour, and use of explicit methods, based on an “a priori” review plan that aims to minimize bias in the analysis and synthesis process (Higgins & Green, 2008). Some reviews are exploratory in nature (e.g., scoping/mapping reviews), whereas others may be conducted to discover patterns (e.g., descriptive reviews) or involve a synthesis approach that may include the critical analysis of prior research ( Paré et al., 2015 ). Hence, in order to select the most appropriate type of review, it is critical to know before embarking on a review project, why the research synthesis is conducted and what type of methods are best aligned with the pursued goals.

9.5. Concluding Remarks

In light of the increased use of evidence-based practice and research generating stronger evidence ( Grady et al., 2011 ; Lyden et al., 2013 ), review articles have become essential tools for summarizing, synthesizing, integrating or critically appraising prior knowledge in the eHealth field. As mentioned earlier, when rigorously conducted review articles represent powerful information sources for eHealth scholars and practitioners looking for state-of-the-art evidence. The typology of literature reviews we used herein will allow eHealth researchers, graduate students and practitioners to gain a better understanding of the similarities and differences between review types.

We must stress that this classification scheme does not privilege any specific type of review as being of higher quality than another ( Paré et al., 2015 ). As explained above, each type of review has its own strengths and limitations. Having said that, we realize that the methodological rigour of any review — be it qualitative, quantitative or mixed — is a critical aspect that should be considered seriously by prospective authors. In the present context, the notion of rigour refers to the reliability and validity of the review process described in section 9.2. For one thing, reliability is related to the reproducibility of the review process and steps, which is facilitated by a comprehensive documentation of the literature search process, extraction, coding and analysis performed in the review. Whether the search is comprehensive or not, whether it involves a methodical approach for data extraction and synthesis or not, it is important that the review documents in an explicit and transparent manner the steps and approach that were used in the process of its development. Next, validity characterizes the degree to which the review process was conducted appropriately. It goes beyond documentation and reflects decisions related to the selection of the sources, the search terms used, the period of time covered, the articles selected in the search, and the application of backward and forward searches ( vom Brocke et al., 2009 ). In short, the rigour of any review article is reflected by the explicitness of its methods (i.e., transparency) and the soundness of the approach used. We refer those interested in the concepts of rigour and quality to the work of Templier and Paré (2015) which offers a detailed set of methodological guidelines for conducting and evaluating various types of review articles.

To conclude, our main objective in this chapter was to demystify the various types of literature reviews that are central to the continuous development of the eHealth field. It is our hope that our descriptive account will serve as a valuable source for those conducting, evaluating or using reviews in this important and growing domain.

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• Cite this Page Paré G, Kitsiou S. Chapter 9 Methods for Literature Reviews. In: Lau F, Kuziemsky C, editors. Handbook of eHealth Evaluation: An Evidence-based Approach [Internet]. Victoria (BC): University of Victoria; 2017 Feb 27.
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What is a Literature Review? How to Write It (with Examples)

A literature review is a critical analysis and synthesis of existing research on a particular topic. It provides an overview of the current state of knowledge, identifies gaps, and highlights key findings in the literature. 1 The purpose of a literature review is to situate your own research within the context of existing scholarship, demonstrating your understanding of the topic and showing how your work contributes to the ongoing conversation in the field. Learning how to write a literature review is a critical tool for successful research. Your ability to summarize and synthesize prior research pertaining to a certain topic demonstrates your grasp on the topic of study, and assists in the learning process. 

Table of Contents

• What is the purpose of literature review? 
• a. Habitat Loss and Species Extinction: 
• b. Range Shifts and Phenological Changes: 
• c. Ocean Acidification and Coral Reefs: 
• d. Adaptive Strategies and Conservation Efforts: 
• How to write a good literature review 
• Choose a Topic and Define the Research Question: 
• Decide on the Scope of Your Review: 
• Select Databases for Searches: 
• Conduct Searches and Keep Track: 
• Review the Literature: 
• Organize and Write Your Literature Review: 
• Frequently asked questions 

What is a literature review?

A well-conducted literature review demonstrates the researcher’s familiarity with the existing literature, establishes the context for their own research, and contributes to scholarly conversations on the topic. One of the purposes of a literature review is also to help researchers avoid duplicating previous work and ensure that their research is informed by and builds upon the existing body of knowledge.

What is the purpose of literature review?

A literature review serves several important purposes within academic and research contexts. Here are some key objectives and functions of a literature review: 2  

• Contextualizing the Research Problem: The literature review provides a background and context for the research problem under investigation. It helps to situate the study within the existing body of knowledge. 
• Identifying Gaps in Knowledge: By identifying gaps, contradictions, or areas requiring further research, the researcher can shape the research question and justify the significance of the study. This is crucial for ensuring that the new research contributes something novel to the field. 
• Understanding Theoretical and Conceptual Frameworks: Literature reviews help researchers gain an understanding of the theoretical and conceptual frameworks used in previous studies. This aids in the development of a theoretical framework for the current research. 
• Providing Methodological Insights: Another purpose of literature reviews is that it allows researchers to learn about the methodologies employed in previous studies. This can help in choosing appropriate research methods for the current study and avoiding pitfalls that others may have encountered. 
• Establishing Credibility: A well-conducted literature review demonstrates the researcher’s familiarity with existing scholarship, establishing their credibility and expertise in the field. It also helps in building a solid foundation for the new research. 
• Informing Hypotheses or Research Questions: The literature review guides the formulation of hypotheses or research questions by highlighting relevant findings and areas of uncertainty in existing literature. 

Literature review example

Let’s delve deeper with a literature review example: Let’s say your literature review is about the impact of climate change on biodiversity. You might format your literature review into sections such as the effects of climate change on habitat loss and species extinction, phenological changes, and marine biodiversity. Each section would then summarize and analyze relevant studies in those areas, highlighting key findings and identifying gaps in the research. The review would conclude by emphasizing the need for further research on specific aspects of the relationship between climate change and biodiversity. The following literature review template provides a glimpse into the recommended literature review structure and content, demonstrating how research findings are organized around specific themes within a broader topic. 

Literature Review on Climate Change Impacts on Biodiversity:

Climate change is a global phenomenon with far-reaching consequences, including significant impacts on biodiversity. This literature review synthesizes key findings from various studies: 

a. Habitat Loss and Species Extinction:

Climate change-induced alterations in temperature and precipitation patterns contribute to habitat loss, affecting numerous species (Thomas et al., 2004). The review discusses how these changes increase the risk of extinction, particularly for species with specific habitat requirements. 

b. Range Shifts and Phenological Changes:

Observations of range shifts and changes in the timing of biological events (phenology) are documented in response to changing climatic conditions (Parmesan & Yohe, 2003). These shifts affect ecosystems and may lead to mismatches between species and their resources. 

c. Ocean Acidification and Coral Reefs:

The review explores the impact of climate change on marine biodiversity, emphasizing ocean acidification’s threat to coral reefs (Hoegh-Guldberg et al., 2007). Changes in pH levels negatively affect coral calcification, disrupting the delicate balance of marine ecosystems. 

d. Adaptive Strategies and Conservation Efforts:

Recognizing the urgency of the situation, the literature review discusses various adaptive strategies adopted by species and conservation efforts aimed at mitigating the impacts of climate change on biodiversity (Hannah et al., 2007). It emphasizes the importance of interdisciplinary approaches for effective conservation planning. 

How to write a good literature review

Writing a literature review involves summarizing and synthesizing existing research on a particular topic. A good literature review format should include the following elements. 

Introduction: The introduction sets the stage for your literature review, providing context and introducing the main focus of your review. 

• Opening Statement: Begin with a general statement about the broader topic and its significance in the field. 
• Scope and Purpose: Clearly define the scope of your literature review. Explain the specific research question or objective you aim to address. 
• Organizational Framework: Briefly outline the structure of your literature review, indicating how you will categorize and discuss the existing research. 
• Significance of the Study: Highlight why your literature review is important and how it contributes to the understanding of the chosen topic. 
• Thesis Statement: Conclude the introduction with a concise thesis statement that outlines the main argument or perspective you will develop in the body of the literature review. 

Body: The body of the literature review is where you provide a comprehensive analysis of existing literature, grouping studies based on themes, methodologies, or other relevant criteria. 

• Organize by Theme or Concept: Group studies that share common themes, concepts, or methodologies. Discuss each theme or concept in detail, summarizing key findings and identifying gaps or areas of disagreement. 
• Critical Analysis: Evaluate the strengths and weaknesses of each study. Discuss the methodologies used, the quality of evidence, and the overall contribution of each work to the understanding of the topic. 
• Synthesis of Findings: Synthesize the information from different studies to highlight trends, patterns, or areas of consensus in the literature. 
• Identification of Gaps: Discuss any gaps or limitations in the existing research and explain how your review contributes to filling these gaps. 
• Transition between Sections: Provide smooth transitions between different themes or concepts to maintain the flow of your literature review. 

Conclusion: The conclusion of your literature review should summarize the main findings, highlight the contributions of the review, and suggest avenues for future research. 

• Summary of Key Findings: Recap the main findings from the literature and restate how they contribute to your research question or objective. 
• Contributions to the Field: Discuss the overall contribution of your literature review to the existing knowledge in the field. 
• Implications and Applications: Explore the practical implications of the findings and suggest how they might impact future research or practice. 
• Recommendations for Future Research: Identify areas that require further investigation and propose potential directions for future research in the field. 
• Final Thoughts: Conclude with a final reflection on the importance of your literature review and its relevance to the broader academic community. 

Conducting a literature review

Conducting a literature review is an essential step in research that involves reviewing and analyzing existing literature on a specific topic. It’s important to know how to do a literature review effectively, so here are the steps to follow: 1  

Choose a Topic and Define the Research Question:

• Select a topic that is relevant to your field of study. 
• Clearly define your research question or objective. Determine what specific aspect of the topic do you want to explore? 

Decide on the Scope of Your Review:

• Determine the timeframe for your literature review. Are you focusing on recent developments, or do you want a historical overview? 
• Consider the geographical scope. Is your review global, or are you focusing on a specific region? 
• Define the inclusion and exclusion criteria. What types of sources will you include? Are there specific types of studies or publications you will exclude? 

Select Databases for Searches:

• Identify relevant databases for your field. Examples include PubMed, IEEE Xplore, Scopus, Web of Science, and Google Scholar. 
• Consider searching in library catalogs, institutional repositories, and specialized databases related to your topic. 

Conduct Searches and Keep Track:

• Develop a systematic search strategy using keywords, Boolean operators (AND, OR, NOT), and other search techniques. 
• Record and document your search strategy for transparency and replicability. 
• Keep track of the articles, including publication details, abstracts, and links. Use citation management tools like EndNote, Zotero, or Mendeley to organize your references. 

Review the Literature:

• Evaluate the relevance and quality of each source. Consider the methodology, sample size, and results of studies. 
• Organize the literature by themes or key concepts. Identify patterns, trends, and gaps in the existing research. 
• Summarize key findings and arguments from each source. Compare and contrast different perspectives. 
• Identify areas where there is a consensus in the literature and where there are conflicting opinions. 
• Provide critical analysis and synthesis of the literature. What are the strengths and weaknesses of existing research? 

Organize and Write Your Literature Review:

• Literature review outline should be based on themes, chronological order, or methodological approaches. 
• Write a clear and coherent narrative that synthesizes the information gathered. 
• Use proper citations for each source and ensure consistency in your citation style (APA, MLA, Chicago, etc.). 
• Conclude your literature review by summarizing key findings, identifying gaps, and suggesting areas for future research. 

The literature review sample and detailed advice on writing and conducting a review will help you produce a well-structured report. But remember that a literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. 

Frequently asked questions

A literature review is a critical and comprehensive analysis of existing literature (published and unpublished works) on a specific topic or research question and provides a synthesis of the current state of knowledge in a particular field. A well-conducted literature review is crucial for researchers to build upon existing knowledge, avoid duplication of efforts, and contribute to the advancement of their field. It also helps researchers situate their work within a broader context and facilitates the development of a sound theoretical and conceptual framework for their studies.

Literature review is a crucial component of research writing, providing a solid background for a research paper’s investigation. The aim is to keep professionals up to date by providing an understanding of ongoing developments within a specific field, including research methods, and experimental techniques used in that field, and present that knowledge in the form of a written report. Also, the depth and breadth of the literature review emphasizes the credibility of the scholar in his or her field.  

Before writing a literature review, it’s essential to undertake several preparatory steps to ensure that your review is well-researched, organized, and focused. This includes choosing a topic of general interest to you and doing exploratory research on that topic, writing an annotated bibliography, and noting major points, especially those that relate to the position you have taken on the topic. 

Literature reviews and academic research papers are essential components of scholarly work but serve different purposes within the academic realm. 3 A literature review aims to provide a foundation for understanding the current state of research on a particular topic, identify gaps or controversies, and lay the groundwork for future research. Therefore, it draws heavily from existing academic sources, including books, journal articles, and other scholarly publications. In contrast, an academic research paper aims to present new knowledge, contribute to the academic discourse, and advance the understanding of a specific research question. Therefore, it involves a mix of existing literature (in the introduction and literature review sections) and original data or findings obtained through research methods. 

Literature reviews are essential components of academic and research papers, and various strategies can be employed to conduct them effectively. If you want to know how to write a literature review for a research paper, here are four common approaches that are often used by researchers.  Chronological Review: This strategy involves organizing the literature based on the chronological order of publication. It helps to trace the development of a topic over time, showing how ideas, theories, and research have evolved.  Thematic Review: Thematic reviews focus on identifying and analyzing themes or topics that cut across different studies. Instead of organizing the literature chronologically, it is grouped by key themes or concepts, allowing for a comprehensive exploration of various aspects of the topic.  Methodological Review: This strategy involves organizing the literature based on the research methods employed in different studies. It helps to highlight the strengths and weaknesses of various methodologies and allows the reader to evaluate the reliability and validity of the research findings.  Theoretical Review: A theoretical review examines the literature based on the theoretical frameworks used in different studies. This approach helps to identify the key theories that have been applied to the topic and assess their contributions to the understanding of the subject.  It’s important to note that these strategies are not mutually exclusive, and a literature review may combine elements of more than one approach. The choice of strategy depends on the research question, the nature of the literature available, and the goals of the review. Additionally, other strategies, such as integrative reviews or systematic reviews, may be employed depending on the specific requirements of the research.

The literature review format can vary depending on the specific publication guidelines. However, there are some common elements and structures that are often followed. Here is a general guideline for the format of a literature review:  Introduction:   Provide an overview of the topic.  Define the scope and purpose of the literature review.  State the research question or objective.  Body:   Organize the literature by themes, concepts, or chronology.  Critically analyze and evaluate each source.  Discuss the strengths and weaknesses of the studies.  Highlight any methodological limitations or biases.  Identify patterns, connections, or contradictions in the existing research.  Conclusion:   Summarize the key points discussed in the literature review.  Highlight the research gap.  Address the research question or objective stated in the introduction.  Highlight the contributions of the review and suggest directions for future research.

Both annotated bibliographies and literature reviews involve the examination of scholarly sources. While annotated bibliographies focus on individual sources with brief annotations, literature reviews provide a more in-depth, integrated, and comprehensive analysis of existing literature on a specific topic. The key differences are as follows: 

References 

• Denney, A. S., & Tewksbury, R. (2013). How to write a literature review.  Journal of criminal justice education ,  24 (2), 218-234. 
• Pan, M. L. (2016).  Preparing literature reviews: Qualitative and quantitative approaches . Taylor & Francis. 
• Cantero, C. (2019). How to write a literature review.  San José State University Writing Center . 

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Literature Reviews

What is a literature review.

• Getting Started
• Searching the Literature
• How to Read Scholarly Studies
• Managing Your Results
• Assembling Your Review

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• Selecting a Topic & Scope
• Identify Keywords to Use in Searching
• Finding Articles
• Reading, Note-taking, and Organization
• Citation Management

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A literature review is a very specific type of academic project. It is not an annotated bibliography. It isn't a research paper. It isn't a comprehensive list of everything ever published on a certain topic. 

Literature reviews are not created to produce new insights. They are written to explore and explain the literature on the topic or issue. 

One of the most important functions of a literature review is to lay the groundwork, provide background and context, for a larger research project such as a Masters thesis or PhD dissertation. Literature reviews often come at the start of scholarly journal articles. In the social sciences and natural sciences, a literature review comprises a section of a scholarly journal article.

Professors in research methods courses often assign standalone literature reviews so that students develop skills in searching, analyzing and organizing scholarly literature in a particular field. 

1. Selecting a Topic & Scope

The first step in any literature review is to identify a topic or subject area you wish to explore, and then setting some parameters to find the scope of your review.

You also need to make sure you select a subject area that has already been researched . It will not be possible to locate sufficient existing literature on a brand new discovery or current event that is being written about in the news right now. It needs to be a well-established research area with existing studies you can review, organize and analyze. Some professors require you to find a topic that has 'not been researched before'. In that case, they don't mean an entire broad topic that hasn't been researched; instead, you'll want to find a sliver of a broad topic that hasn't been researched before. This is where narrowing your topic and finding parameters becomes very important. You may need to do some background reading on several different topics to find one that works, if your professor is having you do a standalone literature review as part of a research methods course.

Ways of Narrowing a Broad topic

For example:

Broad topic: ADHD treatments

Narrowed question: How can neurofeedback be used in threating elementary school-aged children?

Publication Dates

The scope of your review will be a part of refining your topic area or research question. In some disciplines, medicine and health science for example, the publication date of your sources may be extremely important. So, to avoid including outdated clinical recommendations, you may want to limit your review to only the most recent research out there. For other topics, say history or literature, publication date may not be as important - and scholarly research from 20, 30, even 50 years ago may still be relevant and useful today. So it's good idea to consider setting some date ranges for your search, it that is important to your topic.

Whatever your topic area turns out to be, framing the boundaries of your research question ahead of time will make searching and selecting appropriate articles that much easier. 

2. Identify Keywords to Use in Searching

Once you have defined a suitable topic or research question for your review, you will need to create a list of keywords that you will use to search for appropriate studies to include in your review. You will be doing searches through several different databases, Google scholar, or publisher platforms and the terminology used in each may vary. It is especially important to have a good variety of search terms that you can combine in different ways. This will ensure you gather the most relevant sources that cover your topic thoroughly. 

Remember to continue to gather and change your keywords as you read more about your topic!

To start, list synonyms and phrases that have to do with the main words of a research topic:

Example: Is neurofeedback useful in the treatment of ADHD in children?

Now, let's consider the word "useful" in this example topic. What is meant by "useful"? The word itself will not be helpful while searching. Instead, think about what might be useful  in terms of treatment of a child with ADHD. Think about benefits and outcomes and brainstorm a list of words:

3. Finding Articles

Using research guides to find subject specific databases.

For more focused searching of the literature of just one discipline, head over to the Research Guides section of our website. We have  Subject Guides   for all disciplines represented at UTC. Find the subject guide that has most to do with your topic, for example, if you are writing about politics, you'd choose Political Science and Public Service guide. Writing about K-12 schools? Choose Education. Each Subject Guide was created by UTC Librarians and has links to a variety of resources that you have access to.

The databases listed are smaller, specialized search engines that mainly retrieve scholarly articles. You will usually find smaller sets of results for each search you do, but those results will be from a subset of very focused resources.

Subject specific databases are searchable by keywords just like Quick Search. An example is shown in the screenshot below of the APA PsycINFO database using the keywords "neurofeedback therapy" AND "ADHD in children":

APA PsycInfo Database Search:

Using the Quick Search

Quick Search is the main search box located in the center of the Library home page. It covers all formats within our collection (physical and electronic, books, films, articles and more).and all subject areas. It is an excellent tool for locating and accessing scholarly content using keyword searches. Below is an example of how to enter your keywords for an effective search, for our sample topic we typed the words "neurofeedback ADHD children behavior problems":

Quick Search has filters  to narrow to just peer reviewed if you'd like, or you can narrow to a specific format like articles, books, or ebooks. You can also narrow by date. Look for the filters on the left sidebar after you run a search. 

As you browse results. you will notice links below each article that allow you to read the full text on the publisher website. If you decide you would like to use the article in your lit review, download the entire PDF to your device for later use. 

Using Google Scholar

Click the  Databases button (just below the Quick Search box on library's homepage) and look for Google Scholar under Multisubject Databases. Using Google Scholar through the UTC Library links our library subscriptions to your Google Scholar search results- which allows you to see articles with no paywalls if we have access! 

4. Reading, Note-taking, and Organization

1. review the how to read a scholarly article guide.

• Learn about common sections in science and social science articles
• Strategies and tips for reading start by reading the entire Abstract, and feel free to jump down to Discussion to decide if an article should be included in your paper

2. Save yourself time with good note-taking

As you read each study, take notes about the most important findings, key concepts, debates or areas of controversy and common themes you see. These notes will inform how you approach organizing and writing your literature review.

To keep organized, UTC Librarians recommend using a literature review matrix, or spreadsheet, to keep track of the articles you find as you go.  Add columns for the citation (including the URL of the article), and once you read it, track the authors' research question, methods, findings and themes. Importantly, keep track of notes and quotes as you go, and the page numbers you got them from. You will see themes or facts emerge as you read more and more articles. 

Here's an example Literature Review Matrix for you to view. Download a sample matrix as an Excel file and edit with your own sources.

3. Some ideas on how to compile an outline for your review:

After reading and taking notes on the sources you are including in your literature review, you will probably be able to identify common themes or threads that appear throughout. These recurring threads or themes can be very useful in creating a narrative framework for your review to make it easier for your readers to understand what literature exists, what has been learned, and why it is significant. Using our example of Neurofeedback Therapy for Children with ADHD, we might decide to organize our results something like this:

Other questions you might ask yourself as you decide how to outline your literature review: 

• What are the major claims being made about the topic? (There may be several)
• What significant data exists to support / explain the claims?
• Are there connections between the claims / concepts / evidence?
• Are there controversies in the literature? 
• Are there knowledge gaps that have yet to be explored? 

5. Citation Management

For smaller literature review projects, simply keeping a list of your references in Word or Google Docs is probably fine. But for longer projects, or those that are going to form the basis for a thesis or dissertation, many students choose to use citation management software to keep track of, organize, and format their references. The UTC Library supports two main citation management options: Zotero and EndNote. 

Zotero is an open source tool provided by Google. It works well with Chrome and Google Docs and has a really nice, easy to use Chrome extension that allows you to seamlessly add references and full text PDFs to your reference "library" as you do your research. The Library has a guide page that walks you through the basics of downloading, configuring and using Zotero. Visit the link below to get started. 

Zotero Guide Page

EndNote is a very powerful software package with lots of advanced features. It is produced by a commercial publisher and the Library pays a subscription fee to offer it to our students and faculty. It comes in two versions: desktop and cloud-based. (The two versions work together to provide seamless access and redundancy no matter where you are). EndNote can be very labor intensive to configure and use at the beginning, but it offers hundreds of citation styles (most major journals, academic associations and scholarly publishers) and works very well for longer, more complex projects with many references and citations. It integrates really well with Microsoft Word but does not work as well with Google Docs. The Library has basic information on its website about how to download and set up EndNote, but in order to learn it effectively, a workshop or librarian consultation is usually required. Our EndNote information is found a the link below:

EndNote Help Page

The UTC Library is home to a full-service Writing and Communication Center with tutors available to assist you with writing projects at any stage - from outline, to draft, to final manuscript. The WCC has it's own section of the UTC Library website. Check out the link below to learn more about the services they offer and how to go about scheduling an appointment.

UTC Writing and Communication Center

• Next: Getting Started >>
• Last Updated: Sep 19, 2023 8:50 AM
• URL: https://guides.lib.utc.edu/literature-reviews

Memorial Sloan Kettering Library

Systematic Review Service

• Review Types
• How Long Do Reviews Take
• Which Review Type is Right for Me
• Policies for Partnering with an MSK Librarian
• Request to Work with an MSK Librarian
• Your First Meeting with an MSK Librarian
• Covidence Review Software
• Step 1: Form Your Team
• Step 2: Define Your Research Question
• Step 3: Write and Register Your Protocol
• Step 4: Search for Evidence
• Step 5: Screen Your Results
• Step 6: Assess the Quality
• Step 7: Collect the Data
• Step 8: Write and Publish the Review
• Additional Resources

Review Type Definitions

There are many different types of reviews. Here are some of the most common ones the MSK Library assists with:

Narrative reviews , or literature reviews, offer flexibility in regards to "how the research or clinical question is formulated (or the scope of the review established), how literature is evaluated and how the findings are organised and presented." ( Source )

Scoping reviews  "are an ideal tool to determine the scope or coverage of a body of literature on a given topic and give clear indication of the volume of literature and studies available as well as an overview (broad or detailed) of its focus." They require most of the same steps as systematic reviews. ( Source )

Systematic reviews  "[attempt] to collate all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question. [They use] explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made" ( Source )

Meta-analyses  follow "a research process used to systematically synthesise or merge the findings of single, independent studies, using statistical methods to calculate an overall or 'absolute' effect." They adhere to systematic review methods, with an additional statistical analysis. ( Source )

Learn more about these and other kinds of reviews.

Review Type Comparison Table

Different review types have different requirements, scopes, and standards:

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• Last Updated: Mar 28, 2024 10:47 AM
• URL: https://libguides.mskcc.org/systematic-review-service

DNP Nursing Resources: Welcome

• Nursing Databases
• Writing, Citing, and Presenting

Welcome to the DNP Nursing Resources Guide

Welcome to the Nursing Resources guide!  Use this guide to learn what resources to use for nursing research, and to get help with technology, writing, citing, and presenting.  

Technology Assistance

• Office of Information Services (OIS) Help Desk Includes a link to information about your student email account.
• Blackboard Help

Types of Nursing Literature

Systematic reviews.

Also known as "meta-analysis", a systematic review identifies an intervention for a specific disease or other problem in health care, and determines whether or not this intervention works. To do this authors locate, appraise and synthesize evidence from as many relevant scientific studies as possible. They summarize conclusions about effectiveness, and provide a unique collation of the known evidence on a given topic, so that others can easily review the primary studies for any intervention

Empirical research articles 

Usually published in peer-reviewed journals. Although a research article will include a bibliography of other literature reviewed, and may lead you to similar articles, its primary purpose is to present original findings. Look for the following elements

• Introduction
• Research design (participants)
• Discussion of data & methods

Evidence-Based Care Sheets and Evidence-Based Articles

Both evidence-based care sheets and evidence-based articles are similar to review articles (described below). These types of articles focus on summarzing research relating to specific ailments and the efficacy of their treatments, and serve as general overviews.

Review articles

Summarizes and synthesizes the results of many different original studies. Its purpose is to define the state of the literature on a particular topic, and discuss different methodologies for conducting research. Review articles are excellent sources for locating research articles, and contain helpful bibliographies.

Clinical articles

Written for practitioners. Clinical articles might present a particular case study or define a new technique.

(source: Clemens, Rachel, "Library Research Guide for Nursing," Dept. of Nursing, Cal State University)

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• Open access
• Published: 13 December 2023

Attributes of errors, facilitators, and barriers related to rate control of IV medications: a scoping review

• Jeongok Park   ORCID: orcid.org/0000-0003-4978-817X 1 ,
• Sang Bin You   ORCID: orcid.org/0000-0002-1424-4140 2 ,
• Gi Wook Ryu   ORCID: orcid.org/0000-0002-4533-7788 3 &
• Youngkyung Kim   ORCID: orcid.org/0000-0002-3696-5416 4  

Systematic Reviews volume  12 , Article number:  230 ( 2023 ) Cite this article

821 Accesses

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Intravenous (IV) medication is commonly administered and closely associated with patient safety. Although nurses dedicate considerable time and effort to rate the control of IV medications, many medication errors have been linked to the wrong rate of IV medication. Further, there is a lack of comprehensive studies examining the literature on rate control of IV medications. This study aimed to identify the attributes of errors, facilitators, and barriers related to rate control of IV medications by summarizing and synthesizing the existing literature.

This scoping review was conducted using the framework proposed by Arksey and O’Malley and PRISMA-ScR. Overall, four databases—PubMed, Web of Science, EMBASE, and CINAHL—were employed to search for studies published in English before January 2023. We also manually searched reference lists, related journals, and Google Scholar.

A total of 1211 studies were retrieved from the database searches and 23 studies were identified from manual searches, after which 22 studies were selected for the analysis. Among the nine project or experiment studies, two interventions were effective in decreasing errors related to rate control of IV medications. One of them was prospective, continuous incident reporting followed by prevention strategies, and the other encompassed six interventions to mitigate interruptions in medication verification and administration. Facilitators and barriers related to rate control of IV medications were classified as human, design, and system-related contributing factors. The sub-categories of human factors were classified as knowledge deficit, performance deficit, and incorrect dosage or infusion rate. The sub-category of design factor was device. The system-related contributing factors were classified as frequent interruptions and distractions, training, assignment or placement of healthcare providers (HCPs) or inexperienced personnel, policies and procedures, and communication systems between HCPs.

Conclusions

Further research is needed to develop effective interventions to improve IV rate control. Considering the rapid growth of technology in medical settings, interventions and policy changes regarding education and the work environment are necessary. Additionally, each key group such as HCPs, healthcare administrators, and engineers specializing in IV medication infusion devices should perform its role and cooperate for appropriate IV rate control within a structured system.

Peer Review reports

Medication errors are closely associated with patient safety and the quality of care [ 1 , 2 ]. In particular, medication errors, which denote a clinical issue of global importance for patient safety, negatively affect patient morbidity and mortality and lead to delays in discharge [ 3 , 4 ]. The National Health Service in the UK estimates that 237 million medication errors occur each year, of which 66 million cause clinically significant harm [ 5 ]. The US Food and Drug Administration reported that they received more than 100,000 reports each year associated with suspected medication errors [ 6 ]. Additionally, it was estimated that 40,000–98,000 deaths per year in the USA could be attributed to errors by healthcare providers (HCPs) [ 7 ]. Previous studies have revealed that medication errors account for 6–12% of hospital admissions [ 8 ].

Intravenous (IV) medication is a common treatment in hospitalized patient care [ 9 ]. It is used in wards, intensive care units (ICUs), emergency rooms, and outpatient clinics in hospitals [ 9 , 10 ]. As direct HCPs, nurses are integral in patient safety during the IV medication process which could result in unintended errors or violations of recommendations [ 3 ]. As many drugs injected via the IV route include high-risk drugs, such as chemotherapy agents, insulin, and opioids [ 10 ], inappropriate dose administration could lead to adverse events (AEs), such as death and life-threatening events [ 11 , 12 ].

IV medication process is a complex and multistage process. There are 12 stages in the IV medication process, which can be classified as follows: (1) obtain the drug for administration, (2) obtain the diluent, (3) reconstitute the drug in the diluent, (4) take the drug at the patient’s bedside, (5) check for the patient’s allergies, (6) check the route of drug administration, (7) check the drug dose, (8) check the patency of the cannula, (9) expel the air from the syringe, (10) administer the drug, (11) flush the cannula, and (12) sign the prescription chart [ 13 ]. IV medication errors can occur at any of these stages. It is imperative to administer the drug at the correct time and rate during the IV medication process [ 13 ]. The National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) defined an error in IV medication rates as “too fast or too slow rate than that intended” [ 14 ]. Maintaining the correct rate of IV medication is essential for enhancing the effectiveness of IV therapy and reducing AEs [ 9 ].

Infusion pumps are devices designed to improve the accuracy of IV infusions, with drug flow, volume, and timing programmed by HCPs [ 15 ]. A smart pump is an infusion pump with a software package containing a drug library. During programming, the smart pump software warns users about entering drug parameters that deviate from the recommended parameters, such as the type, dose, and dosage unit of the drug [ 15 ]. In the absence of a device for administering IV medication, such as an infusion pump or smart pump, the IV rate is usually controlled by counting the number of fluid drops falling into the drip chamber [ 9 ].

According to the previous study, applying an incorrect rate was the most prevalent IV medication error, accounting for 536 of 925 (57.9%) total IV medication errors [ 16 ]. Although rate control of IV medications is critical to patient safety and quality care, few studies review and map the relevant literature on rate control of IV medications. Therefore, this study aimed to identify the attributes of errors, facilitators, and barriers related to rate control of IV medications by summarizing the existing literature.

The specific research questions of this study are as follows:

What are the general characteristics of the studies related to rate control of IV medications?

What are the attributes of errors associated with rate control of IV medications?

What are the facilitators and barriers to rate control of IV medications?

This scoping review followed the framework suggested by Arksey and O’Malley [ 17 ] and developed by Levac et al. [ 18 ] and Peters et al. [ 19 ]. Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) developed in 2020 by the Joanna Briggs Institute (JBI) were used to ensure reliability in the reporting of methodology (Additional file 1 ) [ 19 ].

Search strategy

According to the JBI Manuals for Evidence Synthesis, a three-step search strategy was adopted [ 19 ]. First, a preliminary search in PubMed was conducted based on the title, abstract, keywords, and index terms of articles to develop our search strategy. In the preliminary search, we used keywords such as “patients,” “nurse,” “IV therapy,” “monitoring,” “rate,” and “medication error.” The search results indicated that studies on medical devices and system-related factors were excluded. Therefore, we decided to exclude the keywords “patients” and “nurse” and focus on “IV therapy,” “monitoring,” “rate,” and “medication error” to comprehensively include studies on factors associated with rate control of infusion medications. Secondly, we used all identified keywords and index terms across all included databases following consultations with a research librarian at Yonsei University Medical Library to elaborate our search strategy. Four databases—PubMed, CINAHL, EMBASE, and Web of Science—were searched using the keywords, index terms, and a comprehensive list of keyword variations to identify relevant studies published before January 2023. The details of the search strategy are described in Additional file 2 . All database search results were exported into Endnote version 20. Finally, we manually searched the reference lists of the included articles identified from the database search. Furthermore, we manually searched two journals related to medication errors and patient safety, and Google Scholar to comprehensively identify the relevant literature. When performing a search on Google Scholar, keywords such as “medication,” “rate,” “IV therapy,” “intravenous administration,” and “medication error” were appropriately combined using search modifiers.

Eligibility criteria

Inclusion criteria were established according to the participants, concept, and context (PCC) framework recommended by the JBI manuals for scoping reviews [ 19 ]. The participants include patients receiving IV therapy, HCPs involved in administering IV medications, and experts from non-healthcare fields related to rate control of IV medications. The concepts were facilitators and barriers to rate control of IV medications, and the contexts were the environments or situations in which errors in rate control of IV medications occurred. While screening the literature identified by the three-step search based on the inclusion criteria, we refined the exclusion criteria through discussion among researchers. The exclusion criteria were as follows: (1) not available in English, (2) not an original article, (3) studies of medication errors in general, (4) not accessible, or (5) prescription error.

Study selection

Once duplicates were automatically removed through Endnote, two independent researchers assessed the eligibility of all articles by screening the titles and abstracts based on the inclusion and exclusion criteria. Studies identified via database searches were screened by GWR and YK and studies identified via other methods were screened by SBY and YK. Full-text articles were obtained either when the studies met the inclusion criteria or when more information was needed to assess eligibility and the researchers independently reviewed the full-text articles. In case of any disagreement in the study selection process, a consensus was reached through discussion among three researchers (GWR, SBY, and YK) and a senior researcher (JP).

Data extraction

Through consensus among the researchers, a form for data extraction was developed to extract appropriate information following the JBI manuals for scoping reviews [ 19 ]. The following data were collected from each study: author information, publication year, country, study design, study period, aims, participants or events (defined as the occurrences related to patient care focused on in the study), contexts, methods, errors related to the control of IV medications (observed results or intervention outcomes), error severity, facilitators, and barriers according to the NCC MERP criteria. Three researchers (GWR SBY, and YK) independently conducted data charting and completed the data extraction form through discussion.

Data synthesis

The general characteristics of included studies such as publication year, country, study design, and study period were analyzed using descriptive statistics to identify trends or patterns. The aims, participants, events, contexts, and methods of the included studies were classified into several categories through a research meeting including a senior researcher (JP) to summarize and analyze the characteristics of the included studies comprehensively. Attributes of errors associated with rate control of IV medications were analyzed and organized through consensus among researchers based on extracted data. Facilitators and barriers to rate control of IV medications were independently classified according to NCC MERP criteria by three researchers (GWR, SBY, and YK) and iteratively modified. Discrepancies were resolved by discussion and re-reading the articles, with the final decision made in consultation with the senior researcher (JP).

A total of 1211 studies were selected through a database search. After reviewing the titles and abstracts of the studies, 42 studies were considered for a detailed assessment by the three researchers. In particular, 2 were not available in English, 3 were not original articles, 24 were studies of medication error in general without details on rate control of IV medications, 2 were regarding prescription errors, and 1 was not accessible. Finally, 10 studies were identified through a database search. Additionally, 23 studies were identified from a manual search. Among the 23, 5 were not original articles, and 6 were studies on medication error in general. Finally, 12 studies were identified via other methods. Hence, 22 studies were included in the data analysis (Fig.  1 , Additional file 3 ).

PRISMA flow chart for literature selection

Characteristics of the studies

General characteristics.

Table 1 presents the general characteristics of the included studies. Two of the included studies had a publication year before 2000 [ 20 , 21 ], and more than half of the studies ( n  = 15) were published in 2010 and later. A majority of the included studies were conducted in Western countries ( n  = 15) [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ], four were conducted in Asia [ 20 , 37 , 38 , 39 ], two were conducted in Australia [ 21 , 40 ], and one was conducted in Egypt [ 2 ]. In terms of the study design, most studies were project studies ( n  = 7) [ 22 , 24 , 27 , 28 , 30 , 34 , 39 ] or prospective observational studies ( n  = 5) [ 2 , 20 , 29 , 32 , 40 ], followed by retrospective studies ( n  = 3) [ 21 , 25 , 35 ], qualitative or mixed-methods studies ( n  = 3) [ 23 , 26 , 33 ], and descriptive cross-sectional studies ( n  = 2) [ 36 , 38 ]. Additionally, there was one controlled pre-posttest study [ 37 ] and one simulation laboratory experiment study [ 31 ]. The study period also varied greatly from 2 days [ 32 ] to 6 years [ 25 ].

The aims of the included studies were divided into two main categories. First, 13 studies identified the current status, causes, and factors influencing errors that could occur in healthcare settings [ 2 , 20 , 21 , 23 , 25 , 26 , 29 , 32 , 33 , 35 , 36 , 38 , 40 ]. Among these, three studies were on errors that may occur in specific healthcare procedures, such as anesthesia [ 20 ], vascular access [ 21 ], and pediatric chemotherapy [ 25 ]. Additionally, three studies explored possible errors associated with specific settings and medications, such as an obstetric emergency ward [ 2 ], cardiac critical care units [ 38 ], and high-alert medications [ 36 ], and three studies investigated the errors associated with the overall IV medication preparation or administration [ 23 , 33 , 40 ]. Moreover, three studies aimed at identifying potential problems associated with the use of IV medication infusion devices [ 26 , 32 , 35 ], and one study was about errors in medication preparation and administration that could occur in a setting using a specific system connected to electronic medical records [ 29 ]. Second, nine studies described the procedure of developing interventions or identified the effect of interventions [ 22 , 24 , 27 , 28 , 30 , 31 , 34 , 37 , 39 ].

Participants and events

Participants in the 22 studies included HCPs such as nurses, doctors, pharmacists, and patients. Notably, four of these studies were only for nurses [ 31 , 37 , 38 , 40 ] and there was also one study involving only pharmacists [ 36 ]. Furthermore, there were five studies wherein people from various departments or roles participated [ 23 , 26 , 27 , 28 , 39 ]. There were three studies wherein the patients were participants, and two studies included both patients and medical staff [ 29 , 33 ].

Among the included studies, nine studies focused on errors in IV medication preparation and administration as events [ 23 , 26 , 30 , 32 , 33 , 34 , 37 , 38 , 40 ] and five studies focused on the administration process only [ 30 , 32 , 34 , 37 , 40 ]. Four studies focused on problems in the administration of all types of drugs including errors associated with rate control of IV medications [ 2 , 22 , 28 , 29 ]. Additionally, four studies focused on events that occurred with IV medication infusion devices [ 24 , 27 , 35 , 39 ], two studies explored the events that occurred during chemotherapy [ 22 , 25 ], and some analyzed events with problems in vascular access [ 21 ], iatrogenic events among neonates [ 28 ], and critical events in anesthesia cases [ 20 ].

Contexts and methods

The contexts can be largely divided into healthcare settings, including hospitals and laboratory settings. Three hospital-based studies were conducted in the entire hospital [ 20 , 22 , 24 ], eight studies were conducted at several hospitals, and the number of hospitals involved varied from 2 to 132 [ 23 , 26 , 32 , 33 , 34 , 35 , 38 , 40 ]. Furthermore, four studies were conducted in different departments within one hospital [ 29 , 30 , 37 , 39 ], three studies were conducted in only one department [ 2 , 27 , 28 ], two studies considered other healthcare settings and were not limited to hospitals [ 21 , 25 ], and one study was conducted in a simulation laboratory setting that enabled a realistic simulation of an ambulatory chemotherapy unit [ 31 ].

Specifically, seven out of the nine studies developed or implemented interventions based on interdisciplinary or multidisciplinary collaboration [ 22 , 24 , 28 , 30 , 34 , 37 , 39 ]. Two studies developed and identified the effectiveness of interventions that created an environment for nurses to improve performance and correct errors associated with medication administration [ 31 , 39 ], and two intervention studies were on error reporting methods or observation tools and the processes of addressing reported errors [ 28 , 30 ]. There were also a study on a pharmacist-led educational program for nurses [ 37 ], a comprehensive intervention from drug prescription to administration to reduce chemotherapy-related medication errors [ 22 ], infusion safety intervention bundles [ 34 ], the implementation of a smart IV pump equipped with failure mode and effects analysis (FMEA) [ 24 ], and a smart system to prevent pump programming errors [ 27 ].

Data collection methods were classified as a review of reported incidents [ 20 , 21 , 22 , 25 , 35 ], a review of medical charts [ 26 ], observations [ 23 , 29 , 30 , 31 , 32 , 33 , 34 , 37 , 40 ], follow-up on every pump alert [ 27 ], and self-reporting questionnaires or surveys [ 36 , 38 ]. Some studies utilized retrospective reviews of reported incidents and self-report questionnaires [ 39 ]. Also, in the study by Kandil et al., observation, nursing records review, and medical charts review were all used [ 2 ].

Attributes of errors associated with rate control of IV medications

Table 2 presents the attributes of errors related to rate control of IV medications in observed results or intervention outcomes, and error severity. Notably, 6 of 13 studies presenting observed results reported errors related to IV medication infusion devices among the rate control errors [ 20 , 25 , 32 , 33 , 35 , 36 ]. Additionally, four studies reported errors in bolus dose administration or IV push and flushing lines among IV rate errors [ 2 , 23 , 36 , 40 ]. Among the 13, nine studies reported error severity, and among these, three studies used NCC MERP ratings [ 25 , 32 , 33 ]. In four studies, error severity was reported by describing several cases in detail [ 2 , 21 , 23 , 25 ], and two studies reported no injuries or damages due to errors [ 26 , 29 ]. Among the nine studies that developed interventions and identified their effectiveness, four presented the frequency of incorrect rate errors as an outcome variable [ 28 , 30 , 34 , 37 ]. Moreover, two studies suggested compliance rates for intervention as outcome variables [ 24 , 31 ].

Among the nine project or experiment studies, three showed a decrease in error rate as a result of the intervention [ 28 , 31 , 34 ]. Three studies developed interventions to reduce rate errors but did not report the frequency or incidence of rate errors [ 22 , 24 , 27 ]. A study reported the frequency of rate errors only after the intervention; the effect of the intervention could not be identified [ 30 ]. Also, three studies showed the severity of errors related to rate control of IV medications [ 24 , 30 , 34 ], two used NCC MERP severity ratings [ 30 , 34 ], and one reported that all errors caused by smart IV pumps equipped with FMEA resulted in either temporary harm or no harm [ 24 ].

Facilitators and barriers to rate control of IV medications

Table 3 presents the facilitators and barriers related to rate control of IV medications according to the NCC MERP taxonomy based on the 22 included studies. Sub-categories of human factors were classified as knowledge deficit, performance deficit, miscalculation of dosage or infusion rate, and stress. The sub-category of design factor was device. System-related contributing factors were classified as frequent interruptions and distractions, inadequate training, poor assignment or placement of HCPs or inexperienced personnel, policies and procedures, and communication systems between HCPs [ 14 ].

Human factors

Among the barriers extracted from the 22 studies, 11 factors belonged to the “knowledge deficit,” “performance deficit,” “miscalculation of dosage or infusion rate,” and “stress (high-volume workload)” in this category. Half of these factors are related to the “performance deficit.” Barriers identified in two or more studies were tubing misplacement [ 24 , 35 ] and non-compliance with protocols and guidelines [ 2 , 25 ], all of which belonged to the “performance deficit.” Additionally, the high workload and environmental characteristics of the ICU, which corresponded to the “stress,” were also identified as barriers to rate control of IV medications [ 23 , 37 ].

Most factors in this category were related to IV medication infusion devices such as infusion pumps and smart pumps. In the study by Lyons et al., the use of devices, such as patient-controlled analgesia pumps and syringe drivers, was a facilitator of rate control of IV medications [ 33 ]. In addition to the use of these devices, the expansion of capabilities [ 26 ], monitoring programming [ 27 ], and standardization [ 22 ] were also facilitators. Unexpected equipment faults, a barrier, were identified in five studies [ 2 , 20 , 25 , 35 , 38 ]. Moreover, the complex design of the equipment [ 23 , 24 ] and incomplete drug libraries in smart pumps [ 33 , 35 ] were identified in two studies each. Factors such as the misassembly of an unfamiliar infusion pump [ 21 ] and smart pumps not connected to electronic systems [ 30 ] were also barriers.

Contributing factors (system related)

The factors belonging to the “frequent interruptions and distractions” in this category were all barriers. Specifically, running multiple infusions at once [ 24 , 27 ], air-in-line alarms, or cleaning air [ 24 ] were identified as barriers. Among the facilitators of the “training,” there were education and training on the use of smart IV pumps [ 24 ] and chemotherapy errors [ 22 ]. There are two factors in the “assignment or placement of a HCP or inexperienced personnel,” where ward-based pharmacists were facilitators [ 36 ], but nurses with less than 6 years of experience were barriers [ 40 ]. The sub-category with the most factors was “policies and procedures,” where the facilitators extracted in the four studies were double-checks through the process [ 22 , 24 , 28 , 36 ]. Among the barriers, two were related to keep-the-vein-open, which was identified in three studies [ 30 , 32 , 33 ]. The lack of automated infusion pumps [ 2 ], the absence of culture for use [ 32 , 33 ], and problems in the drug prescription process [ 33 ] were also identified as barriers. Communication with physicians in instances of doubt identified was the only identified facilitator in the “communication systems between HCPs” [ 28 ].

Resolutions for the barriers to rate control of IV medications

Table 4 presents the resolutions for the barriers to rate control of IV medications in the included studies. The suggested resolutions primarily belonged to the “contributing factors (system-related)” category. Resolutions in the “human factors” category were mainly related to the knowledge and performance of individual healthcare providers, and there were no studies proposing resolutions specifically addressing stress (high-volume workload), which is one of the barriers. Resolutions in the “design” category focused on the development [ 26 , 30 ], appropriate use [ 24 , 33 ], evaluation [ 26 ], improvement [ 24 , 26 , 30 ], and supply [ 23 ] of infusion pumps or smart pumps. Resolutions addressing aspects within the “contributing factors (system-related)” category can be classified into six main areas: interdisciplinary or inter-institution collaboration [ 23 , 25 , 28 , 30 , 34 , 35 , 36 , 37 ], training [ 24 , 37 , 40 ], implementation of policies or procedures [ 29 , 31 , 34 , 35 , 37 , 39 ], system improvement [ 25 , 30 , 32 ], creating a patient safety culture [ 25 , 37 , 38 ], and staffing [ 2 , 38 ].

This scoping review provides the most recent evidence on the attributes of errors, facilitators, and barriers related to rate control of IV medications. The major findings of this study were as follows: (1) there were a few intervention studies that were effective in decreasing the errors related to rate control of IV medications; (2) there was limited research focusing on the errors associated with IV medication infusion devices; (3) a few studies have systematically evaluated and analyzed the severity of errors associated with rate control of IV medications; and (4) the facilitators and barriers related to rate control of IV medications were identified by NCC MERP taxonomy as three categories (human factors, design, and system-related contributing factors).

Among the nine project or experiment studies, only two interventions showed statistically significant effectiveness for IV rate control [ 28 , 31 ]. Six studies did not report the specific statistical significance of the intervention [ 22 , 24 , 27 , 30 , 37 , 39 ], and one study found that the developed intervention had no statistically significant effect [ 34 ]. In another study, administration errors, including rate errors, increased in the experimental group and decreased in the control group [ 37 ]. IV rate control is a major process in medication administration that is comprehensively related to environmental and personal factors [ 3 , 41 ]. According to previous studies, interdisciplinary or multidisciplinary cooperation is associated with the improvement in patient safety and decreased medical errors [ 42 , 43 , 44 ]. Seven of the included studies were also project or experiment studies that developed interventions based on an interdisciplinary or multidisciplinary approach [ 22 , 24 , 28 , 30 , 34 , 37 , 39 ]. Additionally, an effective intervention was developed by a multidisciplinary care quality improvement team [ 28 ]. Therefore, it is crucial to develop effective interventions based on an interdisciplinary or multidisciplinary approach to establish practice guidelines with a high level of evidence related to IV rate control.

Of the 22 included studies, three identified potential problems associated with the use of IV medication infusion devices [ 26 , 32 , 35 ], and four described the application of interventions or explored the effects of the intervention developed to reduce errors that occur when using IV medication infusion devices [ 24 , 27 , 34 , 39 ]. IV medication infusion devices, such as infusion pumps and smart pumps, are widely used in healthcare environments and allow more rigorous control in the process of administering medications that are continuously infused [ 45 ]. Smart pumps are recognized as useful devices for providing safe and effective nursing care [ 15 ]. However, the use of IV medication infusion devices requires an approach different from traditional rate monitoring by counting the number of fluid drops falling into the drip chamber [ 9 ]. However, there exist many problems, such as bypassing the drug library, device maintenance, malfunction, tubing/connection, and programming in the use of IV medication infusion devices [ 32 , 35 ]. None of the four studies that described the application of interventions or explored the effects of the intervention demonstrated statistically significant effects. All four studies had no control group [ 24 , 27 , 34 , 39 ] and two studies had only post-test designs [ 24 , 27 ]. Therefore, further research needs to be conducted to analyze errors in rate control related to IV medication infusion devices and develop effective interventions.

A few studies have systematically evaluated and analyzed the severity of errors associated with rate control of IV medications. Among the 12 studies that reported the severity of errors associated with rate control of IV medications, five studies used NCC MERP, an internationally validated and reliable tool for assessing error severity, and one study used the Severity Assessment Code (SAC) developed by the New South Wales Health Department. Six studies did not use tools to assess error severity. The term “error severity” means the degree of potential or actual harm to patients [ 46 ]. Evaluating the severity of medication errors is a vital point in improving patient safety throughout the medication administration process. This evaluation allows for distinguishing errors based on their severity to establish the development of risk mitigation strategies focused on addressing errors with the great potential to harm patients [ 47 , 48 ]. Specifically, errors associated with rate control of IV medications were categorized as A to E on the NCC MERP and to groups 3 and 4 on the SAC. Additionally, errors associated with rate control of IV medications caused direct physical damage [ 2 , 21 ] and necessitated additional medication to prevent side effects or toxicity [ 23 ]. Therefore, as errors in rate control of IV medications are likely to cause actual or potential harm to the patient, research systematically evaluating and analyzing error severity should be conducted to provide the basis for developing effective risk reduction strategies in the rate control of IV medications.

Facilitators and barriers were identified as human, design, and system-related contributing factors. Among the human factors, “performance deficit” included failure to check equipment properly, tubing misplacement, inadequate monitoring, non-compliance with protocols and guidelines, and human handling errors with smart pumps. Nurses play a major role in drug administration; thus, their monitoring and practices related to IV medication infusion devices can influence patient health outcomes [ 3 , 49 ]. A major reason for the lack of monitoring was overwork, which was related to the complex working environment, work pressure, and high workload [ 3 , 11 , 49 ]. Moreover, two of the included studies identified high workload as a barrier to rate control of IV medications [ 23 , 37 ]. Therefore, to foster adequate monitoring of rate control of IV medications, a systematic approach to alleviating the complex working environment and work pressure should be considered.

Most facilitators and barriers in the devices category were related to IV medication infusion devices. In particular, expanding pump capabilities [ 26 ], monitoring pump programming [ 27 ], standardization [ 22 ], and using a pump [ 33 ] can facilitate rate control of IV medications. However, unexpected equipment faults are significant barriers, as identified in five studies among the included studies [ 2 , 20 , 25 , 35 , 38 ]. Moreover, the design [ 23 , 24 ], user-friendliness [ 21 ], connectivity to electronic systems [ 30 ], and completeness of drug libraries [ 33 , 35 ] are factors that can affect rate control of IV medications. Therefore, it is important to improve, monitor, and manage IV medication infusion devices so that they do not become barriers. Moreover, because rate errors caused by other factors can be prevented by devices, active utilization and systematic management of devices at the system level are required.

Although there are many benefits of infusion and smart pumps for reducing errors in rate control of IV medications, they cannot be used in all hospitals because of the limitation of medical resources. The standard infusion set, which is a device for controlling the rate of IV medication by a controller [ 9 ], is widely used in outpatient as well as inpatient settings [ 32 ]. Devices for monitoring the IV infusion rate, such as FIVA™ (FIVAMed Inc, Halifax, Canada) and DripAssist (Shift Labs Inc, Seattle, USA), which can continuously monitor flow rate and volume with any gravity drip set, have been commercialized [ 33 ]. However, they have not been widely used in hospitals. Therefore, developing novel IV infusion rate monitoring devices that are simple to use, can be used remotely, and are affordable for developing and underdeveloped countries can help nurses to reduce their workloads in monitoring IV infusion rates and thus maintain patient safety.

Most facilitators and barriers were system-related contributing factors, most of which belonged to the “policies and procedures.” In four studies, the absence of hospital policies or culture related to rate control of IV medications was identified as a barrier [ 2 , 30 , 32 , 33 ]. Medication errors related to incorrect rate control are problems that should be approached from macroscopic levels, such as via institutional policies and safety cultures. Therefore, large-scale research including more diverse departments and institutions needs to be conducted.

The second most common categories in system-related contributing factors were “frequent interruptions and distractions” and “training.” Although nurses experienced frequent interruptions and distributions during work, only one of the included studies was on interventions that were developed to create an environment with reduced interruptions [ 31 ]. Additionally, four studies found that education for nurses who are directly associated with medication administration is mandatory [ 22 , 23 , 24 , 36 ]. Therefore, education and a work environment for safety culture should be created to improve IV rate control.

Based on resolutions for barriers to rate control of IV medications, key groups relevant to rate control of IV medications include HCPs, healthcare administrators, and engineers specializing in IV medication infusion devices. HCPs directly involved in the preparation and administration of IV medications need to enhance their knowledge of drugs, raise awareness for the importance of rate control of IV medications, and improve performance related to IV infusion device monitoring. Engineers specializing in IV medication infusion devices should develop these devices by integrating various information technologies used in clinical settings. Additionally, they should identify issues related to these devices and continuously enhance both software and hardware. Healthcare administrators play a crucial role in establishing and leading interdisciplinary or inter-institution collaborations. They should foster leadership, build a patient safety culture within the organization, and implement training, interventions, and policies for correct rate control of IV medications. Decreasing medication errors, including errors in IV rate control, is closely linked to the various key groups [ 50 , 51 , 52 , 53 ], and multidisciplinary collaboration is emphasized for quality care [ 54 , 55 , 56 , 57 ]. Therefore, each key group should perform its role and cooperate for appropriate IV rate control within a structured system.

This review has some limitations that should be considered. As there was no randomized controlled trial in this review, the causal relationship between wrong rate errors and their facilitators or barriers could not be determined. Moreover, only limited literature may have been included in this review because we included literature published in English and excluded gray literature. Since we did not evaluate the quality of the study, there may be a risk of bias in data collection and analysis. Despite these limitations, this study provides a meaningful assessment of published studies related to rate control of IV medications. This contribution will provide an important basis for new patient safety considerations in IV medication administration when determining future policies and device development.

The findings of this review suggest that further research is needed to be conducted to develop effective interventions to improve the practice of IV rate control. Moreover, given the rapid growth of technology in medical settings, research on IV medication infusion devices should be conducted. Additionally, to establish effective risk reduction strategies, it is necessary to systematically evaluate and analyze the severity of errors related to the rate control of IV medications. Several facilitators and barriers to rate control of IV medications were identified in this review to ensure patient safety and quality care, interventions and policy changes related to education and the work environment are required. Additionally, the development of a device capable of monitoring the flow of IV medication is necessary. This review will be useful for HCPs, hospital administrators, and engineers specializing in IV medication infusion devices to minimize errors in rate control of IV medications and improve patient safety.

Availability of data and materials

The corresponding author can provide the datasets that were utilized and/or examined during the present study upon reasonable request.

Abbreviations

Adverse event

Healthcare provider

Intensive care unit

Intravenous

Joanna Briggs Institute

The National Coordinating Council for Medication Error Reporting and Prevention

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L Naseralallah D Stewart M Price V Paudyal 2023 Prevalence, contributing factors, and interventions to reduce medication errors in outpatient and ambulatory settings: a systematic review Int J Clin Pharm https://doi.org/10.1007/s11096-023-01626-5

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This research was supported by the Korea Medical Device Development Fund grant funded by the Korea government (the Ministry of Science and ICT, the Ministry of Trade, Industry and Energy, the Ministry of Health & Welfare, the Ministry of Food and Drug Safety) (Project Number: RS-2020-KD000077) and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. 2020R1A6A1A03041989). This work also supported by the Brain Korea 21 FOUR Project funded by National Research Foundation (NRF) of Korea, Yonsei University College of Nursing.

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Conceptualization: JP; study design: JP; data collection: GWR, YK, SBY; data analysis: JP, GWR, YK, SBY; administration: JP; funding acquisition: JP; writing—original draft: JP, GWR, YK; writing—review and editing: JP, YK.

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Park, J., You, S.B., Ryu, G.W. et al. Attributes of errors, facilitators, and barriers related to rate control of IV medications: a scoping review. Syst Rev 12 , 230 (2023). https://doi.org/10.1186/s13643-023-02386-z

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Received : 15 May 2023

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DOI : https://doi.org/10.1186/s13643-023-02386-z

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Book Review: ‘City of Ruins’ completes a masterful Don Winslow trilogy

This image released by William Morrow shows “City in Ruins” by Don Winslow. (William Morrow via AP)

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Years ago, when novelist Don Winslow first read Aeschylus, he recognized that the Greek father of literary tragedies had explored every major theme found in modern crime fiction, from murder, vengeance, and corruption to power, justice and redemption. He became obsessed, he said recently, with the idea of retelling the ancient stories in a modern-crime fiction trilogy.

For the last 30 years, while churning out a succession of books that include some of the best crime novels ever written, he worked on the ambitious project in fits and starts, sometimes despairing but never giving up.

“City of Ruins” marks the conclusion of his saga of Rhode Island mobster turned Las Vegas gambling tycoon Danny Ryan. If Winslow is to be believed, it is also the last novel he will ever write as he turns his considerable talents to political activism.

The trilogy opened with “City on Fire” (2021) as Ryan and a handful of allies fled Providence, Rhode Island, after losing a gang war to the Italian Mafia. It continued with “City of Dreams” (2023) as Ryan tried, and failed, to build a new life in Los Angeles.

As “City in Ruins” opens, we find an older Ryan operating as a silent partner in two Las Vegas casinos. A man who was once a dock worker and underworld strong arm in Providence is now rich beyond his dreams, but he still wants more.

Why, he wonders. Is it greed? No. Not that.

“Be honest with yourself,” he says. “You want more money because money is power and power is safety. And you can never be safe enough. Not in this world.”

After all, the Italian mob and the FBI are still out there, hell bent on revenge and/or justice for the crimes he’s committed. For the people he has killed.

So Danny overreaches.

He schemes to purchase a prime piece of real estate on the Las Vegas strip to build a fabulous gambling resort, putting him in conflict with the city’s power brokers including a rival casino owner who has mob connections of his own.

Soon, the old enemies also are circling. Danny does what he can to prevent the power struggle from turning violent, but through a series of miscalculations, bullets start flying, endangering not only his gambling empire but his life and the lives of those he loves.

While “City in Ruins” can be read as a standalone, readers would be best served by reading the trilogy from the beginning. With his compelling characters, his vivid prose, and his exploration of universal themes, Winslow has produced a masterpiece of modern crime fiction.

Bruce DeSilva, winner of the Mystery Writers of America’s Edgar Award, is the author of the Mulligan crime novels including “The Dread Line.”

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Title: schrödinger symmetry: a historical review.

Abstract: This paper reviews the history of the conformal extension of Galilean symmetry, now called Schrödinger symmetry. In the physics literature, its discovery is commonly attributed to Jackiw, Niederer and Hagen (1972). However, Schrödinger symmetry has a much older ancestry: the associated conserved quantities were known to Jacobi in 1842/43 and its euclidean counterpart was discovered by Sophus Lie in 1881 in his studies of the heat equation. A convenient way to study Schrödinger symmetry is provided by a non-relativistic Kaluza-Klein-type "Bargmann" framework, first proposed by Eisenhart (1929), but then forgotten and re-discovered by Duval {\it et al.} only in 1984. Representations of Schrödinger symmetry differ by the value $z=2$ of the dynamical exponent from the value $z=1$ found in representations of relativistic conformal invariance. For generic values of $z$, whole families of new algebras exist, which for $z=2/\ell$ include the $\ell$-conformal galilean algebras. We also review the non-relativistic limit of conformal algebras and that this limit leads to the $1$-conformal galilean algebra and not to the Schrödinger algebra. The latter can be recovered in the Bargmann framework through reduction. A distinctive feature of Galilean and Schrödinger symmetries are the Bargmann super-selection rules, algebraically related to a central extension. An empirical consequence of this was known as "mass conservation" already to Lavoisier. As an illustration of these concepts, some applications to physical ageing in simple model systems are reviewed.

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Why do we trust in online reviews? Integrative literature review and future research directions

Vol.17, no.2 (2023).

https://doi.org/10.5817/CP2023-2-7

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Online reviews are an important information source in decision-making processes. Basing decisions on online reviews, however, requires consumers to trust. Consequently, studying trust has become a major research concern. This article provides an integrative literature review of 70 articles published between 2005 and 2021 that, using both quantitative and qualitative approaches, investigated which factors affect trust in the context of online reviews. Results show that research examined 77 different factors for their effect on trust. For most factors—such as integrity of reviewer, quality of argument, and consistency of review with other reviews—, the findings are relatively distinct. The impact of some other factors—such as homophily, two-sidedness of reviews, and emotionality of reviews—is less clear. To synthesize and systematize the results, I develop a conceptual framework based on a model of the online review process. This framework identifies six groups of factors, namely factors related to reviewers, opinion seekers, platforms, communities, option providers, and external actors. On a more general level, the review finds that research uses many different operationalizations of trust, yet rarely embraces more comprehensive concepts of trust. Based on an assessment of the state of the field, I suggest that future research should corroborate, integrate, and expand upon this body of knowledge.

Nils S. Borchers

Institute of media studies, university of tübingen, tübingen, germany.

Nils S. Borchers is a postdoctoral researcher and lecturer at the Chair of Empirical Media Research, Institute of Media Studies at the U of Tübingen. Nils earned his PhD at U of Mannheim and his MA at the U of Münster. His research interests include digital communication, peer-to-peer-communication, strategic communication, and critical advertising studies.

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Author’s Contribution

This study was devised and conducted by Nils S. Borchers.

Editorial Record

First submission received: September 22, 2021

Revisions received: September 28, 2022 February 20, 2023

Accepted for publication: February 22, 2023

Editor in charge: Lenka Dedkova

Introduction

Online reviews of such diverse “objects” as cameras, hotels, physicians, and university lecturers have become a mass phenomenon. Many internet users search through reviews of peer consumers, peer patients, peer students, etc. before taking decisions so that online reviews have gained a considerable impact in many areas of everyday lives (e.g., Chevalier & Mayzlin, 2006; Maslowska et al., 2017). Basing decisions on online reviews requires the trust of opinion seekers in the evaluations of their peers. Accordingly, trust in and credibility of online reviews are of specific importance for explaining the effects of reviews. However, trusting in online reviewers and their reviews is a high-risk undertaking. For example, the opinion seeker usually lacks information on both the reviewer’s motives to provide the review and the reviewer’s qualification to evaluate the reviewed object. Furthermore, the providers of the reviewed objects benefit from positive evaluations of their offerings and thus have strong incentives to influence reviews in their favor (Lappas, 2012). Yet despite these obstacles, surveys indicate that internet users widely trust online reviews: For example, an US industry survey (BrightLocal, 2022) found that 49 percent of consumers trust online reviews as much as they trust personal recommendations from family and friends.

Studying trust has become a main concern in research on online reviews. As this review article will show, I identified 70 research articles published in peer-reviewed journals that examined trust in online review contexts. However, a focused overview of their findings is still missing. There exist various literature reviews (Bore et al., 2017; C. M. K. Cheung & Thandani, 2010; Ismagilova et al., 2020; King et al., 2014; Rani & Shivaprasad, 2018) and conceptual frameworks (Moran & Muzellec, 2017) that address research on electronic word-of-mouth (eWOM) communication. These works are, however, neither focused exclusively on online reviews nor on trust and credibility. To close this gap, this article sets out to provide an integrative literature review of empirical studies on trust in online review contexts. It contributes to the field by collecting existing findings, offering a framework for organizing these findings, and identifying shortcomings and research desiderata to indicate future research directions. 

Theorizing Trust in Online Review Contexts

In this section, I will put forward a suggestion on how to theorize trust in online review contexts. To do so, I will first introduce my theoretical understandings of online reviews and trust. Then, I will bring the two understandings together to develop a framework for organizing the empirical findings in the field.

Online Reviews

Online reviews are usually discussed as a specific format of eWOM communication. eWOM is defined as “consumer-generated, consumption-related communication that employs digital tools and is directed primarily to other consumers“ (Babić Rosario et al., 2020). eWOM thus serves as an umbrella concept that includes not only online reviews, but also other types of computer-mediated peer-consumer conversations. In contrast to other eWOM formats, online reviews are usually posted on specific online review platforms. These platforms can be both integrated within retailer homepages (e.g., Amazon, Bookings), fan communities (e.g., Metalstorm, The Metal Archives), and social networking sites (e.g., Facebook), as well as created independently (e.g., Yelp, HealthGrades). Online reviews have been defined as “peer-generated product evaluations posted on company or third-party websites” (Mudambi & Schuff, 2008, p. 186). For the current study, I heavily draw on this definition but specify that I consider all studies relevant that examine peer evaluations in the review section of a review platform. These reviews may be posted on an actual platform or generated specifically for a scientific study. It should be noted that this approach leads to an exclusion of online reviews published on individual blogs, e.g., by social media influencers. I decided to exclude these reviews because the conditions under which trust in online reviews emerges on review platforms differs markedly from the conditions under which it emerges on blogs.

Trust is a common social phenomenon that can be observed in many, if not all, areas of everyday life. Yet, when trying to pinpoint trust, the fuzziness of the concept becomes apparent. Many researchers have tackled trust from the perspective of their respective fields and presented a wide range of conceptualizations (see Gefen et al., 2003, for an overview). However, many scholars agree that in a trust relationship, a trustor acts on the grounds of the expectation that a trustee acts in a specific way, although the trustee could also act differently (Barber, 1983; Gefen et al., 2003; Giddens, 1990; Hardin, 1992; Luhmann, 1968, 1975/2018; Möllering, 2001). For example, a consumer (aka the trustor) who reads an online review of a camera might expect that the reviewer (aka the trustee) has collected sufficient information about and gained extensive experience of the camera before publishing a review. The tricky point here is that the trustor cannot be sure whether the trustee actually acts in the expected way. This uncertainty makes trust risky because the trustee could always act differently than expected, but the trustor will find out whether the trustee fulfilled their expectations only after having trusted them (Gefen et al., 2003; Luhmann, 1968, 1975/2018). For example, a consumer buys the particular camera just to find out that the reviewer did not discuss relevant dysfunctionalities and weaknesses. Alternatively, some authors highlight the vulnerability of the trustor as a key characteristic of trust (e.g,. McGeer & Pettit, 2017; Mishra, 1996; Rousseau et al., 1998) and thus emphasize the consequences of entering a relationship whose outcomes are uncertain because they depend on the trustee.

For this review, I chose to draw on a concept that was, at its core, developed by Luhmann (1968, 1975/2018). Luhmann shares the definition of trust relationships that I just introduced. Imperative for the Luhmannian understanding of trust then is the notion of “own selectivity” (Luhmann, 1990). The concept of own selectivity starts from the observation that, in most situations, a person faces more than one option how to act and therefore must make a decision. It highlights that only this person can make the decision. In a next analytical step, Luhmann introduces a second person to the situation to highlight the social consequences of own selectivity. In their actions, the second person depends on the first person and therefore has to find ways to cope with the first person’s own selectivity as the general autonomy to decide what to do. For Luhmann, trust is a mechanism that helps the second person (the trustor) to do so by acting on the grounds of the assumption that the first person (the trustee) will act as expected. Other such mechanisms are, for example, familiarity, contracts, and hope (Kohring, 2004). A consequence of this understanding of trust is that trust is always addressed to another social actor such as online reviewers and not to entities without own selectivity such as online reviews. This position also explains why, in trying to be analytically rigorous, I use the somewhat cumbersome formulation “trust in online review contexts” instead of “trust in online reviews.”

Since trusting is a risky business, trustors try to identify reasons to trust (Kohring, 2004). Such reasons serve as legitimation for entering a trust relationship because they reduce the perceived risk. For instance, in the camera example, the educational background of the reviewer or the conformity of a review with other reviews on the same camera may function as reasons to trust. Reasons to trust usually refer to particular dimensions of trust (Kohring, 2004). While trust is regarded as a multidimensional concept (Gefen, 2002; Lewis & Weigert, 1985; Romero & Mitchell, 2017), there exists less consensus about which dimensions constitute trust. Some authors argue in support of general principles that address the risk and vulnerability of the trustor such as benevolence (McKnight & Chervany, 2001; Romero & Mitchell, 2017), honesty (Fukuyama, 1995; Seckler et al., 2015), or reliability (Mishra, 1996; Rotter, 1971). In contrast, Luhmann (1968, 1975/2018) argues that the dimensions of trust depend on the social context of the trust relationship. That is to say that the dimensions of trust will be different in different social contexts. For example, the dimensions of trust in a writer of online reviews differs from those of trust in a judge or in a politician because online review author, judge, and politician fulfill different functions in society. In this review, I follow this second line of reasoning.

A considerable debate in trust research circles around the question whether trust should be considered a belief, an attitude, an intention, or a combination of these (for an overview, see Gefen et al., 2003). The Luhmannian line of understanding trust brings up yet another possibility: From its perspective, trust can be regarded as a social relation between two (or more) persons. Accordingly, it holds that trust emerges in and through the relationship rather than “residing” in the trustor. This perspective allows to adjourn the debate on belief, attitude, and intention without neglecting its relevance.

Luhmann’s concept of trust has proven to be productive for the study of trust in mediated communication (e.g., Graf, 2018; Hoffjann, 2013; Kohring, 2004). Like any other concept, however, Luhmann’s concept opens specific perspectives while, at the same time, suffering from its blind spots. This is why I want to emphasize that there exist other trust concepts (e.g., Barber, 1983; Giddens, 1990; Lewis & Weigert, 1985; McGeer & Pettit, 2017; Möllering, 2001) that are worth exploring and that will open different perspectives on trust in online review contexts. Beyond the question of which particular concept to adopt, I suggest that engaging with more comprehensive concepts of trust is fruitful because it sharpens the analytical capabilities of research on trust in online review contexts.

Trust in Online Review Contexts

As Duffy (2017) pointed out, there are different forms of trust in online review contexts. To identify relevant trust relationships, I employed a model of the ideal online review process (Figure 1). The model identifies the various actors involved in the review process: An option provider (e.g., camera manufacturer or physician) offers a specific option (e.g., camera that can be bought or health treatment that can be received). A reviewer , who, ideally, has experience with using this option, composes a review to share this experience. The review is (usually) published on a platform, provided by a platform provider (e.g., Amazon or Healthgrades). A community of platform users assesses the quality of the review (e.g., via comments, flagging, helpfulness votes). An opinion seeker who is interested in the option consults the review as part of their decision making on whether to select the option. In addition to reading the review, the opinion seeker might collect further information provided by an external actor , i.e., an actor who is neither associated with the platform nor the option. Note also that the model only captures the most basic operation of the online review process, which is one opinion seeker consulting one review. In most cases, the opinion seeker will consult more than one review and compare the reviews with each other.

Figure 1. Model of the Ideal Online Review Process.

Note. White boxes symbolize actors within the process. Gray boxes symbolize cultural artifacts. Arrows symbolize relations between actors and artifacts. Dotted lines frame the core of the online review process. Note that the model indicates relations only for the ideal case in which all actors act in a way that facilitates the best online review quality.

From the perspective of the opinion seeker, the involvement of other actors poses risks due to each actor’s own selectivity: The opinion seeker cannot know whether these actors act in a way that ensures good review quality and thus might disappoint expectations directed toward them. For example, platform providers might sell specific editing options to option providers, option providers might pay reviewers to write tendentious reviews (Gössling et al., 2018), reviewers might be unconsciously biased toward premium brands (de Langhe et al., 2016), and community members might have different views on what constitutes a helpful review. Because of these risks, the opinion seeker needs to trust in one or more of the involved actors if they consult online reviews as a source of information in the decision-making process. This conclusion implies that trust in online review contexts usually goes beyond the sole trust in the reviewer to also involve other actors as trustees. The model of the online review process provides a framework for organizing research on trust in online reviews. It allows for attribution of the examined factors to specific actors in the online review process, by indicating to whose actor’s selective actions the factor refers.

Considering the various actors also helps to reflect on four distinctive features of trust in online review contexts that, in combination, distinguish this setting from offline settings. First, while pooling recommendations in offline settings usually includes familiar trustees such as friends, family members, and colleagues, trust in online review contexts is directed at anonymous strangers such as reviewers and platform communities (Borchers, 2021). This mechanism allows opinion seekers to benefit from the experiences of other internet users beyond local, temporal, and social constraints, yet it comes at the price of drastically reduced familiarity with the trustees. Second, review platforms allow their users to share experiences and thus facilitate trust between strangers. However, they provide not only the technical infrastructure for the online review process, but also the terms and conditions for publishing and accessing online reviews (van Dijck, 2013). These terms and conditions reflect the commercial interests of platform providers. Third, quality management is delegated to the community and usually takes place only after the publication. This is different from other (offline) sources to which opinion seekers could turn such as travel books when looking for accommodation or consumer safety groups when looking for a new smoothie maker. Fourth, the online review process is expected to be a peer-to-peer communication process (Borchers, 2021). Peer-to-peer communication implies that the roles of reviewer and opinion seeker are generally interchangeable. Consequently, all opinion seekers could also act as reviewers and vice versa. Such role flexibility does not exist in most other social contexts, such as traditional advertising or journalism.

Research Questions

Trust in online reviews has emerged as an eminent topic in the research on eWOM. This review article aims at providing an overview of the state of research. First, it addresses the research designs that researchers apply. Research designs determine what researchers can see. For example, standardized surveys make exactly those attitudes, intentions, behaviors etc. visible that the surveys ask for. In contrast, observations do not predefine what is to see and thus expand the perspective of the researcher, yet they usually fail to see the broader picture beyond individual cases because they focus on only a few participants.

RQ1: Which research designs are applied in studies on trust in online review contexts?

Second, this review examines the theoretical conceptualizations that inform studies on trust in online review contexts. Like methods, theoretical conceptualizations allow researchers to see specific aspects of a phenomenon because they direct the view of the researcher.

RQ2: How do studies on trust in online review contexts conceptualize trust?

While the RQ1 and RQ2 provide information on how researchers produced their findings, the third research question aims at the actual findings and accounts for the factors that explain trust in online review contexts.

RQ3: Which factors have which effects on trust in online review contexts?

Methodological Framework: Integrative Literature Review

To answer the research questions, I conducted an integrative literature review (Whittemore & Knafl, 2005). The integrative literature review “reviews, critiques, and synthesizes representative literature on a topic in an integrated way” (Torraco, 2005, p. 356). It aims at generating a summary of research trends as well as new perspectives and frameworks on the reviewed topic (Khoo et al., 2011; Torraco, 2005). The integrative literature review supports my objectives in going beyond the description of existing research and allowing for the application of a new conceptual framework and the development of future research directions.

Data Collection

An appropriate and comprehensive literature search strategy is important for enhancing the rigor of literature reviews. The strategy should allow identification of all relevant articles to ensure that the review is based on an adequate corpus and can yield accurate results (Whittemore & Knafl, 2005).

Online reviews are studied in different disciplines, such as marketing, communication, psychology, information systems, and tourism. To take the diversity of the research field into account, I considered a variety of established international academic databases: (1) Business Source Premier, (2) Communication & Mass Media Complete, (3) PsycARTICLES, (4) PsycINFO, (5) PSYNDEX, (6) Library Information Science and Technology Abstracts, and (7) Web of Science.

Search Term

The research literature discusses online reviews under various labels. I therefore included alternative labels in the search term by varying (a) the term “online” with “internet,” “digital,” and, as a large share of existing studies is interested in consumer behavior, “consumer;” and (b) the term “review” with “rating” and “recommendation.” In addition, I searched for the term “eWOM” or “electronic word-of-mouth” (in different variants) because eWOM is an umbrella concept that includes online reviews. Furthermore, research on trust relies on two theoretical concepts, trust and credibility (Kohring & Matthes, 2007). As the two terms are closely connected, I decided to include both in the search term. These considerations resulted in the search term displayed in Table 1.

Table 1 . Final Search Term for Integrative Literature Review.

Selection Criteria

I included an article in the corpus of this review if it met the following content criteria: (1) The article explains the perception of trust (or credibility, respectively) in an online review or the reviewer (see section 2.1), i.e., it conceptualizes trust in online review contexts as a dependent or mediating variable. Articles that focused on trust in other social actors, such as brands or platforms, were not included. I also did not consider articles that examined trust exclusively as an independent or moderating variable. (2) The article focuses on online reviews. Articles on other eWOM formats, including blog posts, forum postings, or social media commentaries, were excluded. Articles were also excluded if they studied online reviews posted outside of review platforms. If in doubt whether an article studied online reviews, for example if the article addressed eWOM and did not specify the eWOM format, I excluded it to ensure a clean data set. (3) The article presents the results of an empirical study.

Furthermore, I introduced three formal criteria: (4) The article is published in a peer-reviewed scientific journal. (5) The article is published in English. (6) The article is published before January 1, 2021, the cutoff date of the query.

Article Selection

The full text query yielded 1,418 records in the seven databases. The combined Ebsco databases (databases 1–6) produced 626 hits, and Web of Science produced 792 hits. As the first step, I removed all articles that did not meet the formal criteria. 510 records were published in other formats than in peer-reviewed scientific journals, another 22 records were published in languages other than English, while all remaining articles were published before the cutoff date of the query. Applying the formal criteria thus led to the exclusion of 532 records. I then controlled the remaining 886 records for duplicates. This procedure identified 275 duplicates, reducing the number of records to 611. As the next step, I used the content criteria to decide whether the article should be included in the sample. To do so, I reviewed the title, keywords, and abstract. If this information did not suffice to make a decision, I examined the full text of the article. This procedure yielded to the exclusion of another 541 records. The final sample thus comprised 70 articles (see Appendix A). Figure 2 displays the selection process.

Data Analysis

For data analysis, I followed Whittemore and Knafl’s (2005) instructions for integrative literature reviews. They propose the following procedure: (1) Data reduction : I coded the articles for concepts of trust, theories, methods, examined factors, and results. (2) Data display: I synthesized the data from the individual articles and organized it into subgroups. This process was guided by Kohring’s (2004) concept of trust and the online review process model. I put particular attention to the identification of different factors discussed under the same label and similar factors discussed under different labels. (3) Data comparison: I examined the synthesized findings to identify strengths, shortcomings, and desiderata of the field. I placed emphasis on a critical analysis as described by Torraco (2005). (4) Conclusion drawing: I critically assessed the current state of research to develop future research directions.

Figure 2 . Overview of Article Selection Process.

Note. Adapted from Page et al., 2020 (modified).

Corpus Characteristics and Bibliometrics

I identified 70 articles on trust in online review contexts that met the selection criteria. The first article on the topic was published in 2005, but more profound scholarly interest in the topic started growing only in 2011 (see Figure 3). Articles were published in 43 individual journals (see Table 2). The large number of journals indicates a high fragmentation of the research field. Only five journals published more than two articles on the topic.

Figure 3 . Number of Publications per Year of Articles on Trust in Online Review Contexts.

Note . The database search for this literature review was conducted in early 2021 and covers research activities before January 1, 2021. The database search yielded two articles (Bartosiak, 2021; Zhang et al., 2021) that were registered as online first versions for 2020. These articles have been published in a journal issue in the meantime and are thus displayed as 2021 in this figure.

Table 2 . Journals That Have Published Articles on Trust in Online Review Contexts.

Research Designs

Research on trust in online reviews applies several methods (see Table 3). Experiments are the most employed method by far, followed by standardized surveys. Accordingly, there is a predominance of articles that adopt quantitative approaches (64 articles) over articles that adopt qualitative (2 articles) or mixed quantitative-qualitative designs (4 articles). Using student samples is a common procedure in the field (30 studies), although most studies rely on general population samples (49 studies). The samples demonstrate geographical diversity (see Table 4). Most studied review objects are hotels (21 studies), electronics (e.g., cameras, TV sets; 16 studies), and restaurants (15 studies). Many studies, especially surveys, do not specify a review platform, but adopt platform-independent approaches, while some focus on existing platforms. Platforms studied most often are TripAdvisor (12 studies), Amazon (6 studies), and Yelp (5 studies), which clearly indicates a Western bias.

Table 3 . Methods Applied in Studies on Trust in Online Review Contexts.

  Table 4 . Sample Origins in Studies on Trust in Online Review Contexts.

Conceptualizing and Measuring Trust

Few studies are informed by more comprehensive concepts of trust. Although it is admittedly hard to determine what is a “more comprehensive concept” and when such a concept “informs” a study, I identified eight articles that related to a conceptual work on trust at least on the level of a definition of trust and not only in passing. The works by Mayer et al. (1995; 6 references) and McKnight and Chervany (2001; 5 references) found some resonance in the field. This resonance might result from the fact that the first and widely cited study in the field (Smith et al., 2005) is informed by these works.

Trust is more often conceptualized on the level of its operationalization for empirical inquiries. I therefore examined reported scales and items that were used to measure trust. I identified a total number of 46 scales that have been used in the field. 38 scales draw on items that originate from previous research, i.e., studies either adopting a complete scale or combining different scales, while eight studies used their own scales. Although the scale presented by Ohanian (1990, 1991) was used much more frequently than others (informing 15 articles), the variety of scales again suggests a great heterogeneity of the field. Qualitative studies used wordings that are similar to the wordings of items in quantitative studies. Where articles reported questions from interview guides, there was a tendency to ask respondents for trust or trustworthiness directly rather than breaking the concept down to its various dimensions.

Examined Factors and Their Effect on Trust

Research has examined the impact of 77 factors on the emergence of trust in online review contexts. I used the model of the online review process to systemize these factors by organizing them according to the actors upon whose own selectivity they touch. For most factors, this process should be self-evident. For example, I assigned the experience of the reviewer in writing reviews to the reviewer since experience will help a reviewer to compose a sound review. Experience thus indicates that trusting this particular reviewer might be less risky. Yet for some other factors, this process may appear to have less face validity. For example, I sorted status badges that reviewers can earn on some platforms in the category “platform-related factors” and not “reviewer-related factors.” I did this although one might think that the badge indicates that a reviewer is trustworthy. However, it is the platform provider who decides whether the platform awards such badges, who determines what the criteria are for acquiring a badge, and who ensures a robust award process. The same logic applies to some of the factors that I systemized as “community-related.” For example, whether a particular review is consistent with other reviews of the same review object depends on the decision that the other reviewers made when writing their reviews. These other reviewers constitute the community. Obviously, the particular reviewer can also tune in the review to the community’s voice. From the perspective of the opinion seeker, however, the other reviews constitute the background against which to assess the consistency of a particular review. The opinion seeker thus has to determine how to respond to this background: Should they base their own assessment of the particular review on these other reviews, or should they discard them? In other words: The opinion seeker has to decide whether to trust in the community. I therefore categorized the consistency of a particular review with other reviews as a community-related factor.

Reviewer-Related Factors

The most exhaustively studied actor in the field is the reviewer. The opinion seeker’s perception of the reviewer’s states and traits is informed by the review that the reviewer wrote as well as by other information that the reviewer provides on the platform, usually when adding information to the user profile. Table 5 presents the reviewer-related factors that have been examined. Research literature often treats review characteristics independently from the reviewer. However, the reviewer is the author of the review and the review depends on their own selectivity. For example, Bannerjee and Chua (2019) examined how the attractiveness of review titles impacts trust but essentially, it is the reviewer who concocts this title. Table 6 presents the findings on review-related factors as a subset of reviewer-related factors.

Table 5 . Examined Reviewer-Related Factors a .

Table 6 . Examined Review-Related Factors a .

Option Provider-Related Factors

The impact of the provider of the reviewed option has been examined only rudimentarily (see Table 7). Notably, Bae and Lee (2011) found that the type of review object influences trust relationships. This factor should be treated with consideration. While the option provider decides which type of options they offer at a market, the review object itself is not an actor in its own right and thus does not possess own selectivity. According to the trust concept informing this literature review, the type of review object should thus rather be theorized as moderator variables than as independent variable.

Table 7 . Examined Option Provider-Related Factors a .

Platform-Related Factors

Research has examined factors that refer to (1) the platform provider as an actor in the online review process and (2) to the information that a platform offers about other actors. For example, platforms might use algorithms to create meta-information, such as marking suspected non-authentic reviews and reporting the status of a platform user. An understanding of studied platform factors can be gained from Table 8.

Community-Related Factors

With regard to the community, research has focused on two different types of factors: (1) meta-information provided by the community that relates to the quality assessment of the specific review via comments or recommendation ratings (e.g., usefulness and helpfulness), and (2) context information that is derived from considering the specific review and its author within the platform environment, such as the consistency of the specific review with other reviews on the same object or the total number of reviews on the object. Table 9 provides an overview on examined community factors.

Table 8 . Platform-Related Factors a .

  Table 9 . Examined Community-Related Factors a .

External Actors-Related Factors

External actors have only occasionally been considered in the field. The little interest in these factors is not surprising, given that external actors remain outside the core online review process. Table 10 summarizes the findings on this factor category.

Table 10 . Examined External Actor-Related Factors a .

Opinion Seeker-Related Factors

Individual characteristics of the opinion seeker can be associated with their willingness to trust. Studies examined the effects of knowledge, states, and, most often, traits on trust in online review contexts (see Table 11).

Table 11. Examined Opinion Seeker-Related Factors a .

Assessment of the State of Research

Research on online reviews has examined a considerable number of factors and how they influence trust. Figure 4 provides an overview of examined factors and their frequency of their consideration in research. For most factors, the findings are relatively distinct, whereas the impact of some others is less clear. In general, however, the field appears to be rather fragmented and heterogeneous. Research uses many different operationalizations of trust and is spread over various journals and disciplines.

The Role of Theory

This literature review set out to synthesize and systemize the existing findings. At the same time, however, the review also brings to light some of the field’s theoretical shortcomings and empirical gaps. Based on this analysis, the main shortcoming of previous research is a certain lack of awareness and reflection of the research’s formal object “trust” (or “credibility,” respectively). In general, the reviewed studies do not refer to comprehensive concepts of trust (e.g., Barber, 1983; Giddens, 1990; Kohring, 2004; Lewis & Weigert, 1985; Luhmann, 1968, 1975/2018; Möllering, 2001) that could more accurately capture the complexity of trust relationships and help interpret the results. This finding echoes a longstanding dissatisfaction with the state of empirical trust research in general. Already in 1991, Wrightsman (1991, p. 411) cautioned that “the general concept of trust deserves much more theoretical analysis. Measurement has advanced more rapidly than conceptual clarification.” Ten years later, McKnight and Chervany (2001, p. 38) emphasized that in the absence of such theoretical analysis, “the plethora of empirical studies (…) has brought trust research to so confusing a state.” For the sake of this review article, I adapted the trust concept advanced by Luhmann (1968, 1975/2018) and other authors following in his footsteps (e.g., Kohring, 2004; Meyer & Ward, 2013; Morgner, 2018) to the online review context. This is not to say that the line of reasoning on trust that I drew on is the only possible line for informing research on trust in online review contexts. Every theoretical perspective enables researchers to see certain aspects while obscuring others, as does this. Nevertheless, my conceptual choice permits the identification of some unfortunate consequences that result from the scarce engagement with trust concepts.

Figure 4 . Considered Factors in Research on Trust in Online Reviews.

Note. Size of bubble corresponds to frequency of consideration (number of studies) of the factor in research on trust in online reviews.

This review brings to light some of the field’s theoretical shortcomings. First, its scarce engagement with trust concepts leads to a fuzzy understanding of who or what the trustor trusts in. Two trust objects are referenced in the studies, the reviewer and the review itself, and sometimes both. The theoretical foundation proposed here could help to resolve this issue. For example, I argued above that trust refers to the own selectivity of actors and that therefore, trust in online reviews should analytically be attributed to their actions. Unsurprisingly, studies consistently report significant correlations between trustworthiness of reviewer and trust in reviews (e.g., M. Y. Cheung et al., 2009; Clare et al., 2018). Furthermore, the online review process model revealed that there are more actors involved in the process than only reviewer and opinion seeker so that the emergence of trust relationships becomes more complex.

Second, the scarce engagement impacts the possibilities to interpret data in meaningful ways. On the one hand, many scales are imported from research on trust in social contexts other than online reviews. From the perspective of the trust concept adopted in this article, trust depends on expectations that are specific for a social context so that dimensions of trust potentially differ from context to context. This perspective thus increases sensitivity for the risk that imported scales might result in neglecting the peculiarities of trust in online reviews. For instance, the scale used most frequently in the field (Ohanian, 1990, 1991) measures trustworthiness of celebrity endorsers in an advertising and marketing context. It seems at least debatable whether trustors’ expectations about celebrity endorsers are similar to their expectations about online reviewers. For example, different from celebrity endorsers, online reviewers are expected to be independent from the option provider. On the other hand, I found that there is a great heterogeneity of items to measure trust. This heterogeneity makes it difficult to compare findings across studies. The trust concept adopted here can inform the operationalization of trust and protect research from inconsistencies when composing scales of items that relate to trust in different ways, for example to dimensions of trust, reasons to trust, and abstract synonyms of trust (e.g., Ayeh et al., 2013; Dou et al., 2012).

Third, the scarce engagement sometimes obscures how factors relate to one another. For example, I found that in some reviewed studies, manifestations of certain dimensions of trust are actually conceptualized as independent variables, i.e., antecedent of trust. For example, Banerjee and Chua (2019) study the credibility of descriptions as an antecedent of trust. Following Kohring’s (2004) concept of trust, this factor can be identified not as an antecedent but rather as an element of trust because it directly refers to a particular trust dimension that he conceptualizes as “trust in the accuracy of descriptions.”

Fourth, this shortcoming restricts the generalization of research findings. Without an appropriate theoretical foundation that helps clarify the conditions for legitimate generalizations, the validity of findings remains limited to the specific context in which the data was generated. For instance, it remains unresolved whether it is possible to transfer findings from a study on online reviews of hotels to reviews of physicians or electronics.

Empirical Gaps

Besides these conceptual challenges, this literature review identified some empirical gaps. First, many factors and factor combinations have only been examined in one or a very limited number of studies, with regard to single review objects (e.g., restaurants, physicians, films), on one platform, and in one cultural context. Moreover, a substantial number of studies uses student samples. In the face of a lasting replication crisis in social and life sciences (Open Science Collaboration, 2015), a more stable empirical validation of some findings appears preferable.

Second, research has examined the factor categories with different degrees of diligence. Whereas the reviewer and the opinion seeker received much attention, the situation is different for the other actors who are involved in the process. The focus on reviewer and opinion seeker is understandable because these two actors can be said to constitute the basic dyad in online review contexts. As the model of the review process illustrates, however, the other actors also play a role in the emergence of trust.

Third, little is known on how different factors interact with one another. While there are studies that examine interactions (e.g., Craciun & Moore, 2019; Flanagin & Metzger, 2013), a more systematic, comprehensive, and coordinated approach to determining interactions is missing.

Fourth, most studies adopt a deductive approach to identify factors that might possibly be related to trust in online reviews. Exploratory approaches do exist in the field (e.g., Clare et al., 2018; O’Reilly et al., 2016), yet are rare. If accepting the theoretical foundations of this review, trust should be considered as directed toward expectations about other actors’ behaviors that are specific to the social context in which trust relationships emerge (Kohring, 2004). A lack of exploratory studies might consequently result in overlooking relevant factors that are specific to online review contexts and thus cannot be derived from research on trust in other contexts.

Future Research Directions

Based on the analysis of strengths, shortcomings, and gaps, I want to propose three endeavors that I think are worthwhile for advancing the field.

Corroborating the Body of Knowledge

Research findings for most factors are unambiguous. The fact, however, that many factors or factor combinations have been examined only once and in specific online review environments, on specific platforms, and in specific cultural contexts calls for replication studies. Moreover, more comparative studies are needed. Researchers can corroborate initial insights by examining if, for example, the relevance of factors that determine opinion seekers’ willingness to trust differs between decisions to buy a plant detergent and to visit a physician or between Northern American and Eastern Asian cultures.

There are some factors for which the evidence is not clear. These include: non-benevolent motives of the reviewer, homophily (reviewer-related factors), correctness of orthography, quality of review, two-sidedness of review, emotionality of review, trustworthiness of descriptions in the review (review-related factors), trustworthiness of platform, reviewer status indication (platform-related factors), receptive attitude of opinion seeker, and experience of opinion seeker with reviews (opinion seeker-related factors). There are many possible reasons why studies yield diverging results. For example, different review objects, platform environments, or cultural backgrounds might explain differences. In some cases, diverging results may also be due to study designs. In still other cases, diverging results might follow from different operationalizations of trust. The fact that the studies usually differ in more than just one aspect makes it difficult to pinpoint the exact reasons that led to diverging results. Moreover, in the cases of the ambiguous factors, the number of studies—and thus the available data basis—is simply too small to identify patterns and reach informed conclusions. Here, further studies are needed to more precisely determine the influence of these factors. A promising starting point is to explore these factors in qualitative studies that allow to address the respective factors in more detail. For example, adopting thought elicitation techniques such as the think aloud method allows researchers in the field to explore the considerations of opinion seekers while engaging with online reviews.

Interestingly, it is sometimes the qualitative studies that yield contradictory findings. For example, while the majority of studies finds that positive valence increases trust, the qualitative studies by Filieri (2016) and Prendergast et al. (2010) demonstrate that positive valence can also have negative effects on trust if reviews become overly positive. While qualitative studies usually do not claim generalizability of their findings, they still can yield detailed and differentiating insights into the effects of specific factors. In particular, this example shows that it might be instructive to reconsider whether identified effects of factors such as valence are indeed linear.

Integrating the Body of Knowledge

It is necessary to integrate the existing findings from different disciplines that are interested in trust in online review contexts to overcome the fragmentation of the research field. Respective attempts might help to better pool resources because the integration of findings makes it easier to identify true research gaps. To tackle the fragmentation, the framework presented in this article might be further refined and adjusted to more specific research interests. Another promising approach to integrate findings might be meta-analyses because this method allows researchers to determine the effect strengths of trust factors across various quantitative data sets. A key challenge in such an undertaking will, however, be the great heterogeneity in operationalizing trust.

Extending the Body of Knowledge

Extending knowledge on trust in online review contexts is a more extensive task. Regarding the theoretical rigor of research, I suggest that engaging with comprehensive concepts of trust (e.g., Barber, 1983; Giddens, 1990; Kohring, 2004; Lewis & Weigert, 1985; Luhmann, 1968, 1975/2018; McGeer & Pettit, 2017; Möllering, 2001) beyond the level of measures and scales provides a more solid foundation for understanding trust in online review contexts. Researchers need to adjust these concepts to online reviews as a specific context. Specifically, the online review process does not only include reviewer and opinion seeker, but also option provider, platform provider, community, and external actors. All of these actors have their own selectivity and, consequently, they influence the emergence of trust relationships.

With regard to empirical directions, I identify three worthwhile directions for extending the body of knowledge. First, experiments and standardized surveys dominate the field. While these two methods are perfectly apt for studying trust in online reviews, I nevertheless want to argue for a greater methodical variety and a stronger consideration of qualitative approaches, such as problem-centered interviews, Q methodology, think alouds, and virtual ethnographies. Due to their open and exploratory character, qualitative approaches allow identifying factors that are specific to trust in online reviews (Clare et al., 2018). Furthermore, by allowing for a greater consideration of individual rationales, qualitative approaches might yield “thick descriptions” (Geertz, 2017) that help contextualize findings. Another promising approach to advance the field is the use of cognitive neuroscience. Various commentators have highlighted the potential of cognitive neuroscience for trust research (Dimoka, 2010; Gefen et al., 2008). This potential has not yet been tapped in the context of online reviews. The approach rests upon the finding that trust, as well as distrust, spans distinct brain areas (Dimoka, 2010). Researchers have successfully applied neuroscientific procedures to general trust research (Tzieropoulos, 2013), and Krueger and Meyer-Lindenberg (2019) proposed a trust model based on neuroscientific findings. These pioneer works hold the potential to add an innovative angle to the study of trust in the context of online reviews.

Second, it is likely that there exist various types of opinion seekers that differ in the importance they attach to specific factors. While one opinion seeker’s willingness to enter a trust relationship may largely depend on, for example, review valence, emotionality, and prior experience with other reviews, these factors might be of minor importance to other opinion seekers. Duffy (2017) suggests opinion seekers’ trust in their own benevolence and integrity as a possible distinguishing feature. There might also exist various types of opinion seekers regarding different usage situations, e.g., decisions on different review objects or decisions made on mobile devices and on-the-go. I encourage researchers to pay more attention to specific opinion seeker types and usage situations. To tackle this task, explorative approaches should prove instructive as a first step. For instance, the Q methodology allows researchers to reconstruct individual perspectives on trust in online reviews and, on this basis, determine what unites opinion seekers who share common viewpoints.

Third, trust relations emerge and grow over time as they unfold within interaction histories. Since the body of reviewers is multitudinous and reviewers often remain anonymous beyond some basic profile information, it seems unlikely that interaction histories unfold between individual peers in general. Nevertheless, opinion seekers gather experience with platforms and platform communities. I propose that these experiences will have a noticeable impact on the emergence of trust. The opinion seeker’s familiarity with a platform has been examined by three studies (Casaló et al., 2015; Lim & Van Der Heide, 2015; Van Der Heide & Lim, 2016), but in general we know little about how prior experiences with platform and platform communities impact trust. This situation motivates two suggestions: First, future study designs should control for prior experiences of opinion seekers. Second, given the dearth of longitudinal studies in the field, researchers should apply designs that allow tracing the formation of trust around specific platforms and their communities over time.

Limitations

The quality of literature reviews crucially depends on the corpus on which they are based (Whittemore & Knafl, 2005). Although I carefully searched for relevant studies, using a broad search term and databases from various disciplines, I cannot guarantee that I identified every academic publication on trust in online reviews. The formal exclusion of non-peer reviewed journal articles and articles published in languages other than English constitutes an obvious limitation. Furthermore, I synthesized the findings on a rather high level of abstraction. It could be argued that the individual factors that constitute categories in this review should be less condensed. I opted for this level of abstraction because the operationalization of most factors was sufficiently similar to group them into one category. However, a more granular systematization might yield a more detailed picture of the state of research. Finally, this review adopted a strict focus on articles that study trust (or credibility) as a dependent or mediating variable. I did not, however, consider the outcomes of trust relationships like purchase intentions (e.g., S. Wang et al., 2015), review adoption (Lis, 2013), attitude toward the review object (e.g., Grabner-Kräuter & Waiguny, 2015), or willingness to re-visit specific online review platforms (Baker & Kim, 2019). Likewise and to avoid “scope creep” (Booth et al., 2016, p. 98), I did not consider concepts that are or might be related to trust, most notably usefulness and helpfulness of reviews (Clare et al., 2018). Future literature reviews on these concepts might help to draw a more comprehensive picture of the role of trust in the online review process.

Conflict of Interest

The author has no conflicts of interest to declare.

Acknowledgement

The author thanks Sevda Can Arslan (Paderborn University) for her involvement with an early outline of this mansuscript that we presented at the 2016 Annual Conference of the Digital Communication division of the German Communication Association in Braunschweig, Germany. The author also thanks the editorial team of Cyberpsychology: Journal of Psychosocial Research on Cyberspace as well as five anonymous reviewers for sharing their helpful advice and support

Full appendices are available in the pdf version of the manuscript.

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Copyright © 2023 Nils S. Borchers

Vacuum erection device for erectile function rehabilitation after radical prostatectomy: which is the correct schedule? Results from a systematic, scoping review

Affiliations.

• 1 Department of Urology, San Giuseppe Hospital, IRCCS Multimedica, Milano, Italy. [email protected].
• 2 Department of Urology, San Giuseppe Hospital, IRCCS Multimedica, Milano, Italy.
• 3 Maternal Infant and Urologic Sciences, Policlinico Umberto I Hospital, "Sapienza" University of Rome, Rome, Italy.
• 4 Department of Urology, Usl Toscana Sud Est, San Donato Hospital, Arezzo, Italy.
• 5 Department of Urology, A.O.U.I. Verona University, Verona, Italy.
• 6 Department of Surgery, S.H. Ho Urology Center, The Chinese University of Hong Kong, Hong Kong, China.
• 7 Department of Urology, Ng Teng Fong General Hospital, National University Health System, Singapore, Singapore.
• 8 Department of Urology, University Hospital "Ospedali Riuniti" and Polytechnic University of Marche Region, Ancona, Italy.
• PMID: 37085734
• DOI: 10.1038/s41443-023-00700-w

Vacuum erection device (VED), for its capacity to improve the peak flow and elasticity of cavernous arteries, is a well-known tool to improve recovery of erectile function (EF) after radical prostatectomy. Aim of this study is to compare the different therapeutic schemes proposed in literature to find the most effective timing for VED treatment and to evaluate its efficacy alone or associated with phosphodiesterase 5 inhibitors (PDE5i). We performed a systematic review of Literature in October 2022 using MEDLINE, EMBASE, and Cochrane Central Controlled Register of Trials to retrieve all articles dealing with EF rehabilitation after radical prostatectomy (excluding non-English papers, reviews, or meeting abstracts). Patients were divided among those receiving VED alone or combined with other treatments. Study outcomes were compared dividing them between those with follow-up shorter or longer than 12 months. Sixteen papers were included according to selection criteria. Among them, seven were randomized-controlled trials, five were prospective observational studies and four were retrospective. VED alone was evaluated in eight articles, while the remaining papers evaluated the combination of VED with PDE5i. Regarding VED therapeutic protocol, 7/16 studies used it daily. Rehabilitation protocol lasted less than 1 year in 4 studies, up to 12 months in 6 studies and more than 1 year in 6 studies. All the studies show improvement in International Index of Erectile Function Questionnaire (IIEF-5), conservation of penile length and satisfactory intercourses when compared to controls. VED results appear to increase when patients were addressed to VED-dedicated programs to enhance their compliance with the device.

© 2023. The Author(s), under exclusive licence to Springer Nature Limited.

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