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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.

Literature review guide

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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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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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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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Organize the literature review into sections that present themes or identify trends, including relevant theory. You are not trying to list all the material published, but to synthesize and evaluate it according to the guiding concept of your thesis or research question.  

What is a literature review?

A literature review is an account of what has been published on a topic by accredited scholars and researchers. Occasionally you will be asked to write one as a separate assignment, but more often it is part of the introduction to an essay, research report, or thesis. 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

A literature review must do these things:

  • be organized around and related directly to the thesis or research question you are developing
  • synthesize results into a summary of what is and is not known
  • identify areas of controversy in the literature
  • formulate questions that need further research

Ask yourself questions like these:

  • What is the specific thesis, problem, or research question that my literature review helps to define?
  • What type of literature review am I conducting? Am I looking at issues of theory? methodology? policy? quantitative research (e.g. on the effectiveness of a new procedure)? qualitative research (e.g., studies of loneliness among migrant workers)?
  • What is the scope of my literature review? What types of publications am I using (e.g., journals, books, government documents, popular media)? What discipline am I working in (e.g., nursing psychology, sociology, medicine)?
  • How good was my information seeking? Has my search been wide enough to ensure I've found all the relevant material? Has it been narrow enough to exclude irrelevant material? Is the number of sources I've used appropriate for the length of my paper?
  • Have I critically analyzed the literature I use? Do I follow through a set of concepts and questions, comparing items to each other in the ways they deal with them? Instead of just listing and summarizing items, do I assess them, discussing strengths and weaknesses?
  • Have I cited and discussed studies contrary to my perspective?
  • Will the reader find my literature review relevant, appropriate, and useful?

Ask yourself questions like these about each book or article you include:

  • Has the author formulated a problem/issue?
  • Is it clearly defined? Is its significance (scope, severity, relevance) clearly established?
  • Could the problem have been approached more effectively from another perspective?
  • What is the author's research orientation (e.g., interpretive, critical science, combination)?
  • What is the author's theoretical framework (e.g., psychological, developmental, feminist)?
  • What is the relationship between the theoretical and research perspectives?
  • Has the author evaluated the literature relevant to the problem/issue? Does the author include literature taking positions she or he does not agree with?
  • In a research study, how good are the basic components of the study design (e.g., population, intervention, outcome)? How accurate and valid are the measurements? Is the analysis of the data accurate and relevant to the research question? Are the conclusions validly based upon the data and analysis?
  • In material written for a popular readership, does the author use appeals to emotion, one-sided examples, or rhetorically-charged language and tone? Is there an objective basis to the reasoning, or is the author merely "proving" what he or she already believes?
  • How does the author structure the argument? Can you "deconstruct" the flow of the argument to see whether or where it breaks down logically (e.g., in establishing cause-effect relationships)?
  • In what ways does this book or article contribute to our understanding of the problem under study, and in what ways is it useful for practice? What are the strengths and limitations?
  • How does this book or article relate to the specific thesis or question I am developing?

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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.

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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.

Literature review guide

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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 .

Cite this Scribbr article

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How to write a superb literature review

Andy Tay is a freelance writer based in Singapore.

You can also search for this author in PubMed   Google Scholar

Literature reviews are important resources for scientists. They provide historical context for a field while offering opinions on its future trajectory. Creating them can provide inspiration for one’s own research, as well as some practice in writing. But few scientists are trained in how to write a review — or in what constitutes an excellent one. Even picking the appropriate software to use can be an involved decision (see ‘Tools and techniques’). So Nature asked editors and working scientists with well-cited reviews for their tips.

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doi: https://doi.org/10.1038/d41586-020-03422-x

Interviews have been edited for length and clarity.

Updates & Corrections

Correction 09 December 2020 : An earlier version of the tables in this article included some incorrect details about the programs Zotero, Endnote and Manubot. These have now been corrected.

Hsing, I.-M., Xu, Y. & Zhao, W. Electroanalysis 19 , 755–768 (2007).

Article   Google Scholar  

Ledesma, H. A. et al. Nature Nanotechnol. 14 , 645–657 (2019).

Article   PubMed   Google Scholar  

Brahlek, M., Koirala, N., Bansal, N. & Oh, S. Solid State Commun. 215–216 , 54–62 (2015).

Choi, Y. & Lee, S. Y. Nature Rev. Chem . https://doi.org/10.1038/s41570-020-00221-w (2020).

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7 Writing a Literature Review

Hundreds of original investigation research articles on health science topics are published each year. It is becoming harder and harder to keep on top of all new findings in a topic area and – more importantly – to work out how they all fit together to determine our current understanding of a topic. This is where literature reviews come in.

In this chapter, we explain what a literature review is and outline the stages involved in writing one. We also provide practical tips on how to communicate the results of a review of current literature on a topic in the format of a literature review.

7.1 What is a literature review?

Screenshot of journal article

Literature reviews provide a synthesis and evaluation  of the existing literature on a particular topic with the aim of gaining a new, deeper understanding of the topic.

Published literature reviews are typically written by scientists who are experts in that particular area of science. Usually, they will be widely published as authors of their own original work, making them highly qualified to author a literature review.

However, literature reviews are still subject to peer review before being published. Literature reviews provide an important bridge between the expert scientific community and many other communities, such as science journalists, teachers, and medical and allied health professionals. When the most up-to-date knowledge reaches such audiences, it is more likely that this information will find its way to the general public. When this happens, – the ultimate good of science can be realised.

A literature review is structured differently from an original research article. It is developed based on themes, rather than stages of the scientific method.

In the article Ten simple rules for writing a literature review , Marco Pautasso explains the importance of literature reviews:

Literature reviews are in great demand in most scientific fields. Their need stems from the ever-increasing output of scientific publications. For example, compared to 1991, in 2008 three, eight, and forty times more papers were indexed in Web of Science on malaria, obesity, and biodiversity, respectively. Given such mountains of papers, scientists cannot be expected to examine in detail every single new paper relevant to their interests. Thus, it is both advantageous and necessary to rely on regular summaries of the recent literature. Although recognition for scientists mainly comes from primary research, timely literature reviews can lead to new synthetic insights and are often widely read. For such summaries to be useful, however, they need to be compiled in a professional way (Pautasso, 2013, para. 1).

An example of a literature review is shown in Figure 7.1.

Video 7.1: What is a literature review? [2 mins, 11 secs]

Watch this video created by Steely Library at Northern Kentucky Library called ‘ What is a literature review? Note: Closed captions are available by clicking on the CC button below.

Examples of published literature reviews

  • Strength training alone, exercise therapy alone, and exercise therapy with passive manual mobilisation each reduce pain and disability in people with knee osteoarthritis: a systematic review
  • Traveler’s diarrhea: a clinical review
  • Cultural concepts of distress and psychiatric disorders: literature review and research recommendations for global mental health epidemiology

7.2 Steps of writing a literature review

Writing a literature review is a very challenging task. Figure 7.2 summarises the steps of writing a literature review. Depending on why you are writing your literature review, you may be given a topic area, or may choose a topic that particularly interests you or is related to a research project that you wish to undertake.

Chapter 6 provides instructions on finding scientific literature that would form the basis for your literature review.

Once you have your topic and have accessed the literature, the next stages (analysis, synthesis and evaluation) are challenging. Next, we look at these important cognitive skills student scientists will need to develop and employ to successfully write a literature review, and provide some guidance for navigating these stages.

Steps of writing a ltierature review which include: research, synthesise, read abstracts, read papers, evaualte findings and write

Analysis, synthesis and evaluation

Analysis, synthesis and evaluation are three essential skills required by scientists  and you will need to develop these skills if you are to write a good literature review ( Figure 7.3 ). These important cognitive skills are discussed in more detail in Chapter 9.

Diagram with the words analysis, synthesis and evaluation. Under analysis it says taking a process or thing and breaking it down. Under synthesis it says combining elements of separate material and under evaluation it says critiquing a product or process

The first step in writing a literature review is to analyse the original investigation research papers that you have gathered related to your topic.

Analysis requires examining the papers methodically and in detail, so you can understand and interpret aspects of the study described in each research article.

An analysis grid is a simple tool you can use to help with the careful examination and breakdown of each paper. This tool will allow you to create a concise summary of each research paper; see Table 7.1 for an example of  an analysis grid. When filling in the grid, the aim is to draw out key aspects of each research paper. Use a different row for each paper, and a different column for each aspect of the paper ( Tables 7.2 and 7.3 show how completed analysis grid may look).

Before completing your own grid, look at these examples and note the types of information that have been included, as well as the level of detail. Completing an analysis grid with a sufficient level of detail will help you to complete the synthesis and evaluation stages effectively. This grid will allow you to more easily observe similarities and differences across the findings of the research papers and to identify possible explanations (e.g., differences in methodologies employed) for observed differences between the findings of different research papers.

Table 7.1: Example of an analysis grid

A tab;e split into columns with annotated comments

Table 7.3: Sample filled-in analysis grid for research article by Ping and colleagues

Source: Ping, WC, Keong, CC & Bandyopadhyay, A 2010, ‘Effects of acute supplementation of caffeine on cardiorespiratory responses during endurance running in a hot and humid climate’, Indian Journal of Medical Research, vol. 132, pp. 36–41. Used under a CC-BY-NC-SA licence.

Step two of writing a literature review is synthesis.

Synthesis describes combining separate components or elements to form a connected whole.

You will use the results of your analysis to find themes to build your literature review around. Each of the themes identified will become a subheading within the body of your literature review.

A good place to start when identifying themes is with the dependent variables (results/findings) that were investigated in the research studies.

Because all of the research articles you are incorporating into your literature review are related to your topic, it is likely that they have similar study designs and have measured similar dependent variables. Review the ‘Results’ column of your analysis grid. You may like to collate the common themes in a synthesis grid (see, for example Table 7.4 ).

Table showing themes of the article including running performance, rating of perceived exertion, heart rate and oxygen uptake

Step three of writing a literature review is evaluation, which can only be done after carefully analysing your research papers and synthesising the common themes (findings).

During the evaluation stage, you are making judgements on the themes presented in the research articles that you have read. This includes providing physiological explanations for the findings. It may be useful to refer to the discussion section of published original investigation research papers, or another literature review, where the authors may mention tested or hypothetical physiological mechanisms that may explain their findings.

When the findings of the investigations related to a particular theme are inconsistent (e.g., one study shows that caffeine effects performance and another study shows that caffeine had no effect on performance) you should attempt to provide explanations of why the results differ, including physiological explanations. A good place to start is by comparing the methodologies to determine if there are any differences that may explain the differences in the findings (see the ‘Experimental design’ column of your analysis grid). An example of evaluation is shown in the examples that follow in this section, under ‘Running performance’ and ‘RPE ratings’.

When the findings of the papers related to a particular theme are consistent (e.g., caffeine had no effect on oxygen uptake in both studies) an evaluation should include an explanation of why the results are similar. Once again, include physiological explanations. It is still a good idea to compare methodologies as a background to the evaluation. An example of evaluation is shown in the following under ‘Oxygen consumption’.

Annotated paragraphs on running performance with annotated notes such as physiological explanation provided; possible explanation for inconsistent results

7.3 Writing your literature review

Once you have completed the analysis, and synthesis grids and written your evaluation of the research papers , you can combine synthesis and evaluation information to create a paragraph for a literature review ( Figure 7.4 ).

Bubble daigram showing connection between synethesis, evaulation and writing a paragraph

The following paragraphs are an example of combining the outcome of the synthesis and evaluation stages to produce a paragraph for a literature review.

Note that this is an example using only two papers – most literature reviews would be presenting information on many more papers than this ( (e.g., 106 papers in the review article by Bain and colleagues discussed later in this chapter). However, the same principle applies regardless of the number of papers reviewed.

Introduction paragraph showing where evaluation occurs

The next part of this chapter looks at the each section of a literature review and explains how to write them by referring to a review article that was published in Frontiers in Physiology and shown in Figure 7.1. Each section from the published article is annotated to highlight important features of the format of the review article, and identifies the synthesis and evaluation information.

In the examination of each review article section we will point out examples of how the authors have presented certain information and where they display application of important cognitive processes; we will use the colour code shown below:

Colour legend

This should be one paragraph that accurately reflects the contents of the review article.

An annotated abstract divided into relevant background information, identification of the problem, summary of recent literature on topic, purpose of the review

Introduction

The introduction should establish the context and importance of the review

An annotated introduction divided into relevant background information, identification of the issue and overview of points covered

Body of literature review

Annotated body of literature review with following comments annotated on the side: subheadings are included to separate body of review into themes; introductory sentences with general background information; identification of gap in current knowledge; relevant theoretical background information; syntheis of literature relating to the potential importance of cerebral metabolism; an evaluation; identification of gaps in knowledge; synthesis of findings related to human studies; author evaluation

The reference section provides a list of the references that you cited in the body of your review article. The format will depend on the journal of publication as each journal has their own specific referencing format.

It is important to accurately cite references in research papers to acknowledge your sources and ensure credit is appropriately given to authors of work you have referred to. An accurate and comprehensive reference list also shows your readers that you are well-read in your topic area and are aware of the key papers that provide the context to your research.

It is important to keep track of your resources and to reference them consistently in the format required by the publication in which your work will appear. Most scientists will use reference management software to store details of all of the journal articles (and other sources) they use while writing their review article. This software also automates the process of adding in-text references and creating a reference list. In the review article by Bain et al. (2014) used as an example in this chapter, the reference list contains 106 items, so you can imagine how much help referencing software would be. Chapter 5 shows you how to use EndNote, one example of reference management software.

Click the drop down below to review the terms learned from this chapter.

Copyright note:

  • The quotation from Pautasso, M 2013, ‘Ten simple rules for writing a literature review’, PLoS Computational Biology is use under a CC-BY licence. 
  • Content from the annotated article and tables are based on Schubert, MM, Astorino, TA & Azevedo, JJL 2013, ‘The effects of caffeinated ‘energy shots’ on time trial performance’, Nutrients, vol. 5, no. 6, pp. 2062–2075 (used under a CC-BY 3.0 licence ) and P ing, WC, Keong , CC & Bandyopadhyay, A 2010, ‘Effects of acute supplementation of caffeine on cardiorespiratory responses during endurance running in a hot and humid climate’, Indian Journal of Medical Research, vol. 132, pp. 36–41 (used under a CC-BY-NC-SA 4.0 licence ). 

Bain, A.R., Morrison, S.A., & Ainslie, P.N. (2014). Cerebral oxygenation and hyperthermia. Frontiers in Physiology, 5 , 92.

Pautasso, M. (2013). Ten simple rules for writing a literature review. PLoS Computational Biology, 9 (7), e1003149.

How To Do Science Copyright © 2022 by University of Southern Queensland is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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literature review as a step in the scientific method entails

What is a Systematic Literature Review?

A systematic literature review (SLR) is an independent academic method that aims to identify and evaluate all relevant literature on a topic in order to derive conclusions about the question under consideration. "Systematic reviews are undertaken to clarify the state of existing research and the implications that should be drawn from this." (Feak & Swales, 2009, p. 3) An SLR can demonstrate the current state of research on a topic, while identifying gaps and areas requiring further research with regard to a given research question. A formal methodological approach is pursued in order to reduce distortions caused by an overly restrictive selection of the available literature and to increase the reliability of the literature selected (Tranfield, Denyer & Smart, 2003). A special aspect in this regard is the fact that a research objective is defined for the search itself and the criteria for determining what is to be included and excluded are defined prior to conducting the search. The search is mainly performed in electronic literature databases (such as Business Source Complete or Web of Science), but also includes manual searches (reviews of reference lists in relevant sources) and the identification of literature not yet published in order to obtain a comprehensive overview of a research topic.

An SLR protocol documents all the information gathered and the steps taken as part of an SLR in order to make the selection process transparent and reproducible. The PRISMA flow-diagram support you in making the selection process visible.

In an ideal scenario, experts from the respective research discipline, as well as experts working in the relevant field and in libraries, should be involved in setting the search terms . As a rule, the literature is selected by two or more reviewers working independently of one another. Both measures serve the purpose of increasing the objectivity of the literature selection. An SLR must, then, be more than merely a summary of a topic (Briner & Denyer, 2012). As such, it also distinguishes itself from “ordinary” surveys of the available literature. The following table shows the differences between an SLR and an “ordinary” literature review.

  • Charts of BSWL workshop (pdf, 2.88 MB)
  • Listen to the interview (mp4, 12.35 MB)

Differences to "common" literature reviews

What are the objectives of slrs.

  • Avoidance of research redundancies despite a growing amount of publications
  • Identification of research areas, gaps and methods
  • Input for evidence-based management, which allows to base management decisions on scientific methods and findings
  • Identification of links between different areas of researc

Process steps of an SLR

A SLR has several process steps which are defined differently in the literature (Fink 2014, p. 4; Guba 2008, Transfield et al. 2003). We distinguish the following steps which are adapted to the economics and management research area:

1. Defining research questions

Briner & Denyer (2009, p. 347ff.) have developed the CIMO scheme to establish clearly formulated and answerable research questions in the field of economic sciences:

C – CONTEXT:  Which individuals, relationships, institutional frameworks and systems are being investigated?

I – Intervention:  The effects of which event, action or activity are being investigated?

M – Mechanisms:  Which mechanisms can explain the relationship between interventions and results? Under what conditions do these mechanisms take effect?

O – Outcomes:  What are the effects of the intervention? How are the results measured? What are intended and unintended effects?

The objective of the systematic literature review is used to formulate research questions such as “How can a project team be led effectively?”. Since there are numerous interpretations and constructs for “effective”, “leadership” and “project team”, these terms must be particularized.

With the aid of the scheme, the following concrete research questions can be derived with regard to this example:

Under what conditions (C) does leadership style (I) influence the performance of project teams (O)?

Which constructs have an effect upon the influence of leadership style (I) on a project team’s performance (O)?          

Research questions do not necessarily need to follow the CIMO scheme, but they should:

  • ... be formulated in a clear, focused and comprehensible manner and be answerable;
  • ... have been determined prior to carrying out the SLR;
  • ... consist of general and specific questions.

As early as this stage, the criteria for inclusion and exclusion are also defined. The selection of the criteria must be well-grounded. This may include conceptual factors such as a geographical or temporal restrictions, congruent definitions of constructs, as well as quality criteria (journal impact factor > x).

2. Selecting databases and other research sources

The selection of sources must be described and explained in detail. The aim is to find a balance between the relevance of the sources (content-related fit) and the scope of the sources.

In the field of economic sciences, there are a number of literature databases that can be searched as part of an SLR. Some examples in this regard are:

  • Business Source Complete
  • ProQuest One Business
  • Web of Science
  • EconBiz        

Our video " Selecting the right databases " explains how to find relevant databases for your topic.

Literature databases are an important source of research for SLRs, as they can minimize distortions caused by an individual literature selection (selection bias), while offering advantages for a systematic search due to their data structure. The aim is to find all database entries on a topic and thus keep the retrieval bias low (tutorial on retrieval bias ).  Besides articles from scientific journals, it is important to inlcude working papers, conference proceedings, etc to reduce the publication bias ( tutorial on publication bias ).

Our online self-study course " Searching economic databases " explains step 2 und 3.

3. Defining search terms

Once the literature databases and other research sources have been selected, search terms are defined. For this purpose, the research topic/questions is/are divided into blocks of terms of equal ranking. This approach is called the block-building method (Guba 2008, p. 63). The so-called document-term matrix, which lists topic blocks and search terms according to a scheme, is helpful in this regard. The aim is to identify as many different synonyms as possible for the partial terms. A precisely formulated research question facilitates the identification of relevant search terms. In addition, keywords from particularly relevant articles support the formulation of search terms.

A document-term matrix for the topic “The influence of management style on the performance of project teams” is shown in this example .

Identification of headwords and keywords

When setting search terms, a distinction must be made between subject headings and keywords, both of which are described below:

  • appear in the title, abstract and/or text
  • sometimes specified by the author, but in most cases automatically generated
  • non-standardized
  • different spellings and forms (singular/plural) must be searched separately

Subject headings

  • describe the content
  • are generated by an editorial team
  • are listed in a standardized list (thesaurus)
  • may comprise various keywords
  • include different spellings
  • database-specific

Subject headings are a standardized list of words that are generated by the specialists in charge of some databases. This so-called index of subject headings (thesaurus) helps searchers find relevant articles, since the headwords indicate the content of a publication. By contrast, an ordinary keyword search does not necessarily result in a content-related fit, since the database also displays articles in which, for example, a word appears once in the abstract, even though the article’s content does not cover the topic.

Nevertheless, searches using both headwords and keywords should be conducted, since some articles may not yet have been assigned headwords, or errors may have occurred during the assignment of headwords. 

To add headwords to your search in the Business Source Complete database, please select the Thesaurus tab at the top. Here you can find headwords in a new search field and integrate them into your search query. In the search history, headwords are marked with the addition DE (descriptor).

The EconBiz database of the German National Library of Economics (ZBW – Leibniz Information Centre for Economics), which also contains German-language literature, has created its own index of subject headings with the STW Thesaurus for Economics . Headwords are integrated into the search by being used in the search query.

Since the indexes of subject headings divide terms into synonyms, generic terms and sub-aspects, they facilitate the creation of a document-term matrix. For this purpose it is advisable to specify in the document-term matrix the origin of the search terms (STW Thesaurus for Economics, Business Source Complete, etc.).

Searching in literature databases

Once the document-term matrix has been defined, the search in literature databases begins. It is recommended to enter each word of the document-term matrix individually into the database in order to obtain a good overview of the number of hits per word. Finally, all the words contained in a block of terms are linked with the Boolean operator OR and thereby a union of all the words is formed. The latter are then linked with each other using the Boolean operator AND. In doing so, each block should be added individually in order to see to what degree the number of hits decreases.

Since the search query must be set up separately for each database, tools such as  LitSonar  have been developed to enable a systematic search across different databases. LitSonar was created by  Professor Dr. Ali Sunyaev (Institute of Applied Informatics and Formal Description Methods – AIFB) at the Karlsruhe Institute of Technology.

Advanced search

Certain database-specific commands can be used to refine a search, for example, by taking variable word endings into account (*) or specifying the distance between two words, etc. Our overview shows the most important search commands for our top databases.

Additional searches in sources other than literature databases

In addition to literature databases, other sources should also be searched. Fink (2014, p. 27) lists the following reasons for this:

  • the topic is new and not yet included in indexes of subject headings;
  • search terms are not used congruently in articles because uniform definitions do not exist;
  • some studies are still in the process of being published, or have been completed, but not published.

Therefore, further search strategies are manual search, bibliographic analysis, personal contacts and academic networks (Briner & Denyer, p. 349). Manual search means that you go through the source information of relevant articles and supplement your hit list accordingly. In addition, you should conduct a targeted search for so-called gray literature, that is, literature not distributed via the book trade, such as working papers from specialist areas and conference reports. By including different types of publications, the so-called publication bias (DBWM video “Understanding publication bias” ) – that is, distortions due to exclusive use of articles from peer-reviewed journals – should be kept to a minimum.

The PRESS-Checklist can support you to check the correctness of your search terms.

4. Merging hits from different databases

In principle, large amounts of data can be easily collected, structured and sorted with data processing programs such as Excel. Another option is to use literature management programs such as EndNote, Citavi or Zotero. The Saxon State and University Library Dresden (SLUB Dresden) provides an  overview of current literature management programs  . Software for qualitative data analysis such as NVivo is equally suited for data processing. A comprehensive overview of the features of different tools that support the SLR process can be found in Bandara et al. (2015).

Our online-self study course "Managing literature with Citavi" shows you how to use the reference management software Citavi.

When conducting an SLR, you should specify for each hit the database from which it originates and the date on which the query was made. In addition, you should always indicate how many hits you have identified in the various databases or, for example, by manual search.

Exporting data from literature databases

Exporting from literature databases is very easy. In  Business Source Complete  , you must first click on the “Share” button in the hit list, then “Email a link to download exported results” at the very bottom and then select the appropriate format for the respective literature program.

In the  Web of Science  database, you must select “Export” and select the relevant format. Tip: You can adjust the extracted data fields. Since for example the abstract is not automatically exported, decide which data fields are of interest for you.

Exporting data from the literature database  EconBiz  is somewhat more complex. Here you must first create a marked list and then select each hit individually and add it to the marked list. Afterwards, articles on the list can be exported.

After merging all hits from the various databases, duplicate entries (duplicates) are deleted.

5. Applying inclusion and exclusion criteria

All publications are evaluated in the literature management program applying the previously defined criteria for inclusion and exclusion. Only those sources that survive this selection process will subsequently be analyzed. The review process and inclusion criteria should be tested with a small sample and adjustments made if necessary before applying it to all articles. In the ideal case, even this selection would be carried out by more than one person, with each working independently of one another. It needs to be made clear how discrepancies between reviewers are dealt with. 

The review of the criteria for inclusion and exclusion is primarily based on the title, abstract and subject headings in the databases, as well as on the keywords provided by the authors of a publication in the first step. In a second step the whole article / source will be read.

Within the Citavi literature-management program, you can supplement title data by adding your own fields. In this regard, the criteria for inclusion can be listed individually and marked with 0 in the free text field for being “not fulfilled” and with 1 for being “fulfilled”. In the table view of all titles, you can use the column function to select which columns should be displayed. Here you can include the criteria for inclusion. By exporting the title list to Excel, it is easy to calculate how many titles remain when applying the criteria for inclusion and exclusion.

In addition to the common literature management tools, you can also use software tools that have been developed to support SLRs. The central library of the university in Zurich has published an overview and evaluation of different tools based on a survey among researchers. --> View SLR tools

The selection process needs to be made transparent. The PRISMA flow diagram supports the visualization of the number of included / excluded studies.

Forward and backward search

Should it become apparent that the number of sources found is relatively small, or if you wish to proceed with particular thoroughness, a forward-and-backward search based on the sources found is recommendable (Webster & Watson 2002, p. xvi). A backward search means going through the bibliographies of the sources found. A forward search, by contrast, identifies articles that have cited the relevant publications. The Web of Science and Scopus databases can be used to perform citation analyses.

6. Perform the review

As the next step, the remaining titles are analyzed as to their content by reading them several times in full. Information is extracted according to defined criteria and the quality of the publications is evaluated. If the data extraction is carried out by more than one person, a training ensures that there will be no differences between the reviewers.

Depending on the research questions there exist diffent methods for data abstraction (content analysis, concept matrix etc.). A so-called concept matrix can be used to structure the content of information (Webster & Watson 2002, p. xvii). The image to the right gives an example of a concept matrix according to Becker (2014).

Particularly in the field of economic sciences, the evaluation of a study’s quality cannot be performed according to a generally valid scheme, such as those existing in the field of medicine, for instance. Quality assessment therefore depends largely on the research questions.

Based on the findings of individual studies, a meta-level is then applied to try to understand what similarities and differences exist between the publications, what research gaps exist, etc. This may also result in the development of a theoretical model or reference framework.

Example concept matrix (Becker 2013) on the topic Business Process Management

7. synthesizing results.

Once the review has been conducted, the results must be compiled and, on the basis of these, conclusions derived with regard to the research question (Fink 2014, p. 199ff.). This includes, for example, the following aspects:

  • historical development of topics (histogram, time series: when, and how frequently, did publications on the research topic appear?);
  • overview of journals, authors or specialist disciplines dealing with the topic;
  • comparison of applied statistical methods;
  • topics covered by research;
  • identifying research gaps;
  • developing a reference framework;
  • developing constructs;
  • performing a meta-analysis: comparison of the correlations of the results of different empirical studies (see for example Fink 2014, p. 203 on conducting meta-analyses)

Publications about the method

Bandara, W., Furtmueller, E., Miskon, S., Gorbacheva, E., & Beekhuyzen, J. (2015). Achieving Rigor in Literature Reviews: Insights from Qualitative Data Analysis and Tool-Support.  Communications of the Association for Information Systems . 34(8), 154-204.

Booth, A., Papaioannou, D., and Sutton, A. (2012)  Systematic approaches to a successful literature review.  London: Sage.

Briner, R. B., & Denyer, D. (2012). Systematic Review and Evidence Synthesis as a Practice and Scholarship Tool. In Rousseau, D. M. (Hrsg.),  The Oxford Handbook of Evidenence Based Management . (S. 112-129). Oxford: Oxford University Press.

Durach, C. F., Wieland, A., & Machuca, Jose A. D. (2015). Antecedents and dimensions of supply chain robustness: a systematic literature review . International Journal of Physical Distribution & Logistic Management , 46 (1/2), 118-137. doi:  https://doi.org/10.1108/IJPDLM-05-2013-0133

Feak, C. B., & Swales, J. M. (2009). Telling a Research Story: Writing a Literature Review.  English in Today's Research World 2.  Ann Arbor: University of Michigan Press. doi:  10.3998/mpub.309338

Fink, A. (2014).  Conducting Research Literature Reviews: From the Internet to Paper  (4. Aufl.). Los Angeles, London, New Delhi, Singapore, Washington DC: Sage Publication.

Fisch, C., & Block, J. (2018). Six tips for your (systematic) literature review in business and management research.  Management Review Quarterly,  68, 103–106 (2018).  doi.org/10.1007/s11301-018-0142-x

Guba, B. (2008). Systematische Literaturrecherche.  Wiener Medizinische Wochenschrift , 158 (1-2), S. 62-69. doi:  doi.org/10.1007/s10354-007-0500-0  Hart, C.  Doing a literature review: releasing the social science research imagination.  London: Sage.

Jesson, J. K., Metheson, L. & Lacey, F. (2011).  Doing your Literature Review - traditional and Systematic Techniques . Los Angeles, London, New Delhi, Singapore, Washington DC: Sage Publication.

Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. doi: 10.1136/bmj.n71.

Petticrew, M. and Roberts, H. (2006).  Systematic Reviews in the Social Sciences: A Practical Guide . Oxford:Blackwell. Ridley, D. (2012).  The literature review: A step-by-step guide . 2nd edn. London: Sage. 

Chang, W. and Taylor, S.A. (2016), The Effectiveness of Customer Participation in New Product Development: A Meta-Analysis,  Journal of Marketing , American Marketing Association, Los Angeles, CA, Vol. 80 No. 1, pp. 47–64.

Tranfield, D., Denyer, D. & Smart, P. (2003). Towards a methodology for developing evidence-informed management knowledge by means of systematic review.  British Journal of Management , 14 (3), S. 207-222. doi:  https://doi.org/10.1111/1467-8551.00375

Webster, J., & Watson, R. T. (2002). Analyzing the Past to Prepare for the Future: Writing a Literature Review.  Management Information Systems Quarterly , 26(2), xiii-xxiii.  http://www.jstor.org/stable/4132319

Durach, C. F., Wieland, A. & Machuca, Jose. A. D. (2015). Antecedents and dimensions of supply chain robustness: a systematic literature review. International Journal of Physical Distribution & Logistics Management, 45(1/2), 118 – 137.

What is particularly good about this example is that search terms were defined by a number of experts and the review was conducted by three researchers working independently of one another. Furthermore, the search terms used have been very well extracted and the procedure of the literature selection very well described.

On the downside, the restriction to English-language literature brings the language bias into play, even though the authors consider it to be insignificant for the subject area.

Bos-Nehles, A., Renkema, M. & Janssen, M. (2017). HRM and innovative work behaviour: a systematic literature review. Personnel Review, 46(7), pp. 1228-1253

  • Only very specific keywords used
  • No precise information on how the review process was carried out (who reviewed articles?)
  • Only journals with impact factor (publication bias)

Jia, F., Orzes, G., Sartor, M. & Nassimbeni, G. (2017). Global sourcing strategy and structure: towards a conceptual framework. International Journal of Operations & Production Management, 37(7), 840-864

  • Research questions are explicitly presented
  • Search string very detailed
  • Exact description of the review process
  • 2 persons conducted the review independently of each other

Franziska Klatt

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literature review as a step in the scientific method entails

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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
  • Last Updated: Oct 26, 2022 2:49 PM
  • URL: https://guides.lib.utexas.edu/literaturereviews

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Book cover

Principles and Practice of Clinical Trials pp 2159–2177 Cite as

Introduction to Systematic Reviews

  • Tianjing Li 3 ,
  • Ian J. Saldanha 4 &
  • Karen A. Robinson 5  
  • Reference work entry
  • First Online: 20 July 2022

196 Accesses

A systematic review identifies and synthesizes all relevant studies that fit prespecified criteria to answer a research question. Systematic review methods can be used to answer many types of research questions. The type of question most relevant to trialists is the effects of treatments and is thus the focus of this chapter. We discuss the motivation for and importance of performing systematic reviews and their relevance to trialists. We introduce the key steps in completing a systematic review, including framing the question, searching for and selecting studies, collecting data, assessing risk of bias in included studies, conducting a qualitative synthesis and a quantitative synthesis (i.e., meta-analysis), grading the certainty of evidence, and writing the systematic review report. We also describe how to identify systematic reviews and how to assess their methodological rigor. We discuss the challenges and criticisms of systematic reviews, and how technology and innovations, combined with a closer partnership between trialists and systematic reviewers, can help identify effective and safe evidence-based practices more quickly.

  • Systematic review
  • Meta-analysis
  • Research synthesis
  • Evidence-based
  • Risk of bias

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Li, T., Saldanha, I.J., Robinson, K.A. (2022). Introduction to Systematic Reviews. In: Piantadosi, S., Meinert, C.L. (eds) Principles and Practice of Clinical Trials. Springer, Cham. https://doi.org/10.1007/978-3-319-52636-2_194

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Defining the process to literature searching in systematic reviews: a literature review of guidance and supporting studies

Chris cooper.

1 Institute of Health Research, University of Exeter Medical School, Exeter, UK

Andrew Booth

2 HEDS, School of Health and Related Research (ScHARR), University of Sheffield, Sheffield, UK

Jo Varley-Campbell

Nicky britten.

3 Institute of Health Research, University of Exeter Medical School, Exeter, UK

Ruth Garside

4 European Centre for Environment and Human Health, University of Exeter Medical School, Truro, UK

Associated Data

Systematic literature searching is recognised as a critical component of the systematic review process. It involves a systematic search for studies and aims for a transparent report of study identification, leaving readers clear about what was done to identify studies, and how the findings of the review are situated in the relevant evidence.

Information specialists and review teams appear to work from a shared and tacit model of the literature search process. How this tacit model has developed and evolved is unclear, and it has not been explicitly examined before.

The purpose of this review is to determine if a shared model of the literature searching process can be detected across systematic review guidance documents and, if so, how this process is reported in the guidance and supported by published studies.

A literature review.

Two types of literature were reviewed: guidance and published studies. Nine guidance documents were identified, including: The Cochrane and Campbell Handbooks. Published studies were identified through ‘pearl growing’, citation chasing, a search of PubMed using the systematic review methods filter, and the authors’ topic knowledge.

The relevant sections within each guidance document were then read and re-read, with the aim of determining key methodological stages. Methodological stages were identified and defined. This data was reviewed to identify agreements and areas of unique guidance between guidance documents. Consensus across multiple guidance documents was used to inform selection of ‘key stages’ in the process of literature searching.

Eight key stages were determined relating specifically to literature searching in systematic reviews. They were: who should literature search, aims and purpose of literature searching, preparation, the search strategy, searching databases, supplementary searching, managing references and reporting the search process.

Conclusions

Eight key stages to the process of literature searching in systematic reviews were identified. These key stages are consistently reported in the nine guidance documents, suggesting consensus on the key stages of literature searching, and therefore the process of literature searching as a whole, in systematic reviews. Further research to determine the suitability of using the same process of literature searching for all types of systematic review is indicated.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0545-3) contains supplementary material, which is available to authorized users.

Systematic literature searching is recognised as a critical component of the systematic review process. It involves a systematic search for studies and aims for a transparent report of study identification, leaving review stakeholders clear about what was done to identify studies, and how the findings of the review are situated in the relevant evidence.

Information specialists and review teams appear to work from a shared and tacit model of the literature search process. How this tacit model has developed and evolved is unclear, and it has not been explicitly examined before. This is in contrast to the information science literature, which has developed information processing models as an explicit basis for dialogue and empirical testing. Without an explicit model, research in the process of systematic literature searching will remain immature and potentially uneven, and the development of shared information models will be assumed but never articulated.

One way of developing such a conceptual model is by formally examining the implicit “programme theory” as embodied in key methodological texts. The aim of this review is therefore to determine if a shared model of the literature searching process in systematic reviews can be detected across guidance documents and, if so, how this process is reported and supported.

Identifying guidance

Key texts (henceforth referred to as “guidance”) were identified based upon their accessibility to, and prominence within, United Kingdom systematic reviewing practice. The United Kingdom occupies a prominent position in the science of health information retrieval, as quantified by such objective measures as the authorship of papers, the number of Cochrane groups based in the UK, membership and leadership of groups such as the Cochrane Information Retrieval Methods Group, the HTA-I Information Specialists’ Group and historic association with such centres as the UK Cochrane Centre, the NHS Centre for Reviews and Dissemination, the Centre for Evidence Based Medicine and the National Institute for Clinical Excellence (NICE). Coupled with the linguistic dominance of English within medical and health science and the science of systematic reviews more generally, this offers a justification for a purposive sample that favours UK, European and Australian guidance documents.

Nine guidance documents were identified. These documents provide guidance for different types of reviews, namely: reviews of interventions, reviews of health technologies, reviews of qualitative research studies, reviews of social science topics, and reviews to inform guidance.

Whilst these guidance documents occasionally offer additional guidance on other types of systematic reviews, we have focused on the core and stated aims of these documents as they relate to literature searching. Table  1 sets out: the guidance document, the version audited, their core stated focus, and a bibliographical pointer to the main guidance relating to literature searching.

Guidance documents audited for this literature review

Once a list of key guidance documents was determined, it was checked by six senior information professionals based in the UK for relevance to current literature searching in systematic reviews.

Identifying supporting studies

In addition to identifying guidance, the authors sought to populate an evidence base of supporting studies (henceforth referred to as “studies”) that contribute to existing search practice. Studies were first identified by the authors from their knowledge on this topic area and, subsequently, through systematic citation chasing key studies (‘pearls’ [ 1 ]) located within each key stage of the search process. These studies are identified in Additional file  1 : Appendix Table 1. Citation chasing was conducted by analysing the bibliography of references for each study (backwards citation chasing) and through Google Scholar (forward citation chasing). A search of PubMed using the systematic review methods filter was undertaken in August 2017 (see Additional file 1 ). The search terms used were: (literature search*[Title/Abstract]) AND sysrev_methods[sb] and 586 results were returned. These results were sifted for relevance to the key stages in Fig.  1 by CC.

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The key stages of literature search guidance as identified from nine key texts

Extracting the data

To reveal the implicit process of literature searching within each guidance document, the relevant sections (chapters) on literature searching were read and re-read, with the aim of determining key methodological stages. We defined a key methodological stage as a distinct step in the overall process for which specific guidance is reported, and action is taken, that collectively would result in a completed literature search.

The chapter or section sub-heading for each methodological stage was extracted into a table using the exact language as reported in each guidance document. The lead author (CC) then read and re-read these data, and the paragraphs of the document to which the headings referred, summarising section details. This table was then reviewed, using comparison and contrast to identify agreements and areas of unique guidance. Consensus across multiple guidelines was used to inform selection of ‘key stages’ in the process of literature searching.

Having determined the key stages to literature searching, we then read and re-read the sections relating to literature searching again, extracting specific detail relating to the methodological process of literature searching within each key stage. Again, the guidance was then read and re-read, first on a document-by-document-basis and, secondly, across all the documents above, to identify both commonalities and areas of unique guidance.

Results and discussion

Our findings.

We were able to identify consensus across the guidance on literature searching for systematic reviews suggesting a shared implicit model within the information retrieval community. Whilst the structure of the guidance varies between documents, the same key stages are reported, even where the core focus of each document is different. We were able to identify specific areas of unique guidance, where a document reported guidance not summarised in other documents, together with areas of consensus across guidance.

Unique guidance

Only one document provided guidance on the topic of when to stop searching [ 2 ]. This guidance from 2005 anticipates a topic of increasing importance with the current interest in time-limited (i.e. “rapid”) reviews. Quality assurance (or peer review) of literature searches was only covered in two guidance documents [ 3 , 4 ]. This topic has emerged as increasingly important as indicated by the development of the PRESS instrument [ 5 ]. Text mining was discussed in four guidance documents [ 4 , 6 – 8 ] where the automation of some manual review work may offer efficiencies in literature searching [ 8 ].

Agreement between guidance: Defining the key stages of literature searching

Where there was agreement on the process, we determined that this constituted a key stage in the process of literature searching to inform systematic reviews.

From the guidance, we determined eight key stages that relate specifically to literature searching in systematic reviews. These are summarised at Fig. ​ Fig.1. 1 . The data extraction table to inform Fig. ​ Fig.1 1 is reported in Table  2 . Table ​ Table2 2 reports the areas of common agreement and it demonstrates that the language used to describe key stages and processes varies significantly between guidance documents.

The order of literature search methods as presented in the guidance documents

For each key stage, we set out the specific guidance, followed by discussion on how this guidance is situated within the wider literature.

Key stage one: Deciding who should undertake the literature search

The guidance.

Eight documents provided guidance on who should undertake literature searching in systematic reviews [ 2 , 4 , 6 – 11 ]. The guidance affirms that people with relevant expertise of literature searching should ‘ideally’ be included within the review team [ 6 ]. Information specialists (or information scientists), librarians or trial search co-ordinators (TSCs) are indicated as appropriate researchers in six guidance documents [ 2 , 7 – 11 ].

How the guidance corresponds to the published studies

The guidance is consistent with studies that call for the involvement of information specialists and librarians in systematic reviews [ 12 – 26 ] and which demonstrate how their training as ‘expert searchers’ and ‘analysers and organisers of data’ can be put to good use [ 13 ] in a variety of roles [ 12 , 16 , 20 , 21 , 24 – 26 ]. These arguments make sense in the context of the aims and purposes of literature searching in systematic reviews, explored below. The need for ‘thorough’ and ‘replicable’ literature searches was fundamental to the guidance and recurs in key stage two. Studies have found poor reporting, and a lack of replicable literature searches, to be a weakness in systematic reviews [ 17 , 18 , 27 , 28 ] and they argue that involvement of information specialists/ librarians would be associated with better reporting and better quality literature searching. Indeed, Meert et al. [ 29 ] demonstrated that involving a librarian as a co-author to a systematic review correlated with a higher score in the literature searching component of a systematic review [ 29 ]. As ‘new styles’ of rapid and scoping reviews emerge, where decisions on how to search are more iterative and creative, a clear role is made here too [ 30 ].

Knowing where to search for studies was noted as important in the guidance, with no agreement as to the appropriate number of databases to be searched [ 2 , 6 ]. Database (and resource selection more broadly) is acknowledged as a relevant key skill of information specialists and librarians [ 12 , 15 , 16 , 31 ].

Whilst arguments for including information specialists and librarians in the process of systematic review might be considered self-evident, Koffel and Rethlefsen [ 31 ] have questioned if the necessary involvement is actually happening [ 31 ].

Key stage two: Determining the aim and purpose of a literature search

The aim: Five of the nine guidance documents use adjectives such as ‘thorough’, ‘comprehensive’, ‘transparent’ and ‘reproducible’ to define the aim of literature searching [ 6 – 10 ]. Analogous phrases were present in a further three guidance documents, namely: ‘to identify the best available evidence’ [ 4 ] or ‘the aim of the literature search is not to retrieve everything. It is to retrieve everything of relevance’ [ 2 ] or ‘A systematic literature search aims to identify all publications relevant to the particular research question’ [ 3 ]. The Joanna Briggs Institute reviewers’ manual was the only guidance document where a clear statement on the aim of literature searching could not be identified. The purpose of literature searching was defined in three guidance documents, namely to minimise bias in the resultant review [ 6 , 8 , 10 ]. Accordingly, eight of nine documents clearly asserted that thorough and comprehensive literature searches are required as a potential mechanism for minimising bias.

The need for thorough and comprehensive literature searches appears as uniform within the eight guidance documents that describe approaches to literature searching in systematic reviews of effectiveness. Reviews of effectiveness (of intervention or cost), accuracy and prognosis, require thorough and comprehensive literature searches to transparently produce a reliable estimate of intervention effect. The belief that all relevant studies have been ‘comprehensively’ identified, and that this process has been ‘transparently’ reported, increases confidence in the estimate of effect and the conclusions that can be drawn [ 32 ]. The supporting literature exploring the need for comprehensive literature searches focuses almost exclusively on reviews of intervention effectiveness and meta-analysis. Different ‘styles’ of review may have different standards however; the alternative, offered by purposive sampling, has been suggested in the specific context of qualitative evidence syntheses [ 33 ].

What is a comprehensive literature search?

Whilst the guidance calls for thorough and comprehensive literature searches, it lacks clarity on what constitutes a thorough and comprehensive literature search, beyond the implication that all of the literature search methods in Table ​ Table2 2 should be used to identify studies. Egger et al. [ 34 ], in an empirical study evaluating the importance of comprehensive literature searches for trials in systematic reviews, defined a comprehensive search for trials as:

  • a search not restricted to English language;
  • where Cochrane CENTRAL or at least two other electronic databases had been searched (such as MEDLINE or EMBASE); and
  • at least one of the following search methods has been used to identify unpublished trials: searches for (I) conference abstracts, (ii) theses, (iii) trials registers; and (iv) contacts with experts in the field [ 34 ].

Tricco et al. (2008) used a similar threshold of bibliographic database searching AND a supplementary search method in a review when examining the risk of bias in systematic reviews. Their criteria were: one database (limited using the Cochrane Highly Sensitive Search Strategy (HSSS)) and handsearching [ 35 ].

Together with the guidance, this would suggest that comprehensive literature searching requires the use of BOTH bibliographic database searching AND supplementary search methods.

Comprehensiveness in literature searching, in the sense of how much searching should be undertaken, remains unclear. Egger et al. recommend that ‘investigators should consider the type of literature search and degree of comprehension that is appropriate for the review in question, taking into account budget and time constraints’ [ 34 ]. This view tallies with the Cochrane Handbook, which stipulates clearly, that study identification should be undertaken ‘within resource limits’ [ 9 ]. This would suggest that the limitations to comprehension are recognised but it raises questions on how this is decided and reported [ 36 ].

What is the point of comprehensive literature searching?

The purpose of thorough and comprehensive literature searches is to avoid missing key studies and to minimize bias [ 6 , 8 , 10 , 34 , 37 – 39 ] since a systematic review based only on published (or easily accessible) studies may have an exaggerated effect size [ 35 ]. Felson (1992) sets out potential biases that could affect the estimate of effect in a meta-analysis [ 40 ] and Tricco et al. summarize the evidence concerning bias and confounding in systematic reviews [ 35 ]. Egger et al. point to non-publication of studies, publication bias, language bias and MEDLINE bias, as key biases [ 34 , 35 , 40 – 46 ]. Comprehensive searches are not the sole factor to mitigate these biases but their contribution is thought to be significant [ 2 , 32 , 34 ]. Fehrmann (2011) suggests that ‘the search process being described in detail’ and that, where standard comprehensive search techniques have been applied, increases confidence in the search results [ 32 ].

Does comprehensive literature searching work?

Egger et al., and other study authors, have demonstrated a change in the estimate of intervention effectiveness where relevant studies were excluded from meta-analysis [ 34 , 47 ]. This would suggest that missing studies in literature searching alters the reliability of effectiveness estimates. This is an argument for comprehensive literature searching. Conversely, Egger et al. found that ‘comprehensive’ searches still missed studies and that comprehensive searches could, in fact, introduce bias into a review rather than preventing it, through the identification of low quality studies then being included in the meta-analysis [ 34 ]. Studies query if identifying and including low quality or grey literature studies changes the estimate of effect [ 43 , 48 ] and question if time is better invested updating systematic reviews rather than searching for unpublished studies [ 49 ], or mapping studies for review as opposed to aiming for high sensitivity in literature searching [ 50 ].

Aim and purpose beyond reviews of effectiveness

The need for comprehensive literature searches is less certain in reviews of qualitative studies, and for reviews where a comprehensive identification of studies is difficult to achieve (for example, in Public health) [ 33 , 51 – 55 ]. Literature searching for qualitative studies, and in public health topics, typically generates a greater number of studies to sift than in reviews of effectiveness [ 39 ] and demonstrating the ‘value’ of studies identified or missed is harder [ 56 ], since the study data do not typically support meta-analysis. Nussbaumer-Streit et al. (2016) have registered a review protocol to assess whether abbreviated literature searches (as opposed to comprehensive literature searches) has an impact on conclusions across multiple bodies of evidence, not only on effect estimates [ 57 ] which may develop this understanding. It may be that decision makers and users of systematic reviews are willing to trade the certainty from a comprehensive literature search and systematic review in exchange for different approaches to evidence synthesis [ 58 ], and that comprehensive literature searches are not necessarily a marker of literature search quality, as previously thought [ 36 ]. Different approaches to literature searching [ 37 , 38 , 59 – 62 ] and developing the concept of when to stop searching are important areas for further study [ 36 , 59 ].

The study by Nussbaumer-Streit et al. has been published since the submission of this literature review [ 63 ]. Nussbaumer-Streit et al. (2018) conclude that abbreviated literature searches are viable options for rapid evidence syntheses, if decision-makers are willing to trade the certainty from a comprehensive literature search and systematic review, but that decision-making which demands detailed scrutiny should still be based on comprehensive literature searches [ 63 ].

Key stage three: Preparing for the literature search

Six documents provided guidance on preparing for a literature search [ 2 , 3 , 6 , 7 , 9 , 10 ]. The Cochrane Handbook clearly stated that Cochrane authors (i.e. researchers) should seek advice from a trial search co-ordinator (i.e. a person with specific skills in literature searching) ‘before’ starting a literature search [ 9 ].

Two key tasks were perceptible in preparing for a literature searching [ 2 , 6 , 7 , 10 , 11 ]. First, to determine if there are any existing or on-going reviews, or if a new review is justified [ 6 , 11 ]; and, secondly, to develop an initial literature search strategy to estimate the volume of relevant literature (and quality of a small sample of relevant studies [ 10 ]) and indicate the resources required for literature searching and the review of the studies that follows [ 7 , 10 ].

Three documents summarised guidance on where to search to determine if a new review was justified [ 2 , 6 , 11 ]. These focused on searching databases of systematic reviews (The Cochrane Database of Systematic Reviews (CDSR) and the Database of Abstracts of Reviews of Effects (DARE)), institutional registries (including PROSPERO), and MEDLINE [ 6 , 11 ]. It is worth noting, however, that as of 2015, DARE (and NHS EEDs) are no longer being updated and so the relevance of this (these) resource(s) will diminish over-time [ 64 ]. One guidance document, ‘Systematic reviews in the Social Sciences’, noted, however, that databases are not the only source of information and unpublished reports, conference proceeding and grey literature may also be required, depending on the nature of the review question [ 2 ].

Two documents reported clearly that this preparation (or ‘scoping’) exercise should be undertaken before the actual search strategy is developed [ 7 , 10 ]).

The guidance offers the best available source on preparing the literature search with the published studies not typically reporting how their scoping informed the development of their search strategies nor how their search approaches were developed. Text mining has been proposed as a technique to develop search strategies in the scoping stages of a review although this work is still exploratory [ 65 ]. ‘Clustering documents’ and word frequency analysis have also been tested to identify search terms and studies for review [ 66 , 67 ]. Preparing for literature searches and scoping constitutes an area for future research.

Key stage four: Designing the search strategy

The Population, Intervention, Comparator, Outcome (PICO) structure was the commonly reported structure promoted to design a literature search strategy. Five documents suggested that the eligibility criteria or review question will determine which concepts of PICO will be populated to develop the search strategy [ 1 , 4 , 7 – 9 ]. The NICE handbook promoted multiple structures, namely PICO, SPICE (Setting, Perspective, Intervention, Comparison, Evaluation) and multi-stranded approaches [ 4 ].

With the exclusion of The Joanna Briggs Institute reviewers’ manual, the guidance offered detail on selecting key search terms, synonyms, Boolean language, selecting database indexing terms and combining search terms. The CEE handbook suggested that ‘search terms may be compiled with the help of the commissioning organisation and stakeholders’ [ 10 ].

The use of limits, such as language or date limits, were discussed in all documents [ 2 – 4 , 6 – 11 ].

Search strategy structure

The guidance typically relates to reviews of intervention effectiveness so PICO – with its focus on intervention and comparator - is the dominant model used to structure literature search strategies [ 68 ]. PICOs – where the S denotes study design - is also commonly used in effectiveness reviews [ 6 , 68 ]. As the NICE handbook notes, alternative models to structure literature search strategies have been developed and tested. Booth provides an overview on formulating questions for evidence based practice [ 69 ] and has developed a number of alternatives to the PICO structure, namely: BeHEMoTh (Behaviour of interest; Health context; Exclusions; Models or Theories) for use when systematically identifying theory [ 55 ]; SPICE (Setting, Perspective, Intervention, Comparison, Evaluation) for identification of social science and evaluation studies [ 69 ] and, working with Cooke and colleagues, SPIDER (Sample, Phenomenon of Interest, Design, Evaluation, Research type) [ 70 ]. SPIDER has been compared to PICO and PICOs in a study by Methley et al. [ 68 ].

The NICE handbook also suggests the use of multi-stranded approaches to developing literature search strategies [ 4 ]. Glanville developed this idea in a study by Whitting et al. [ 71 ] and a worked example of this approach is included in the development of a search filter by Cooper et al. [ 72 ].

Writing search strategies: Conceptual and objective approaches

Hausner et al. [ 73 ] provide guidance on writing literature search strategies, delineating between conceptually and objectively derived approaches. The conceptual approach, advocated by and explained in the guidance documents, relies on the expertise of the literature searcher to identify key search terms and then develop key terms to include synonyms and controlled syntax. Hausner and colleagues set out the objective approach [ 73 ] and describe what may be done to validate it [ 74 ].

The use of limits

The guidance documents offer direction on the use of limits within a literature search. Limits can be used to focus literature searching to specific study designs or by other markers (such as by date) which limits the number of studies returned by a literature search. The use of limits should be described and the implications explored [ 34 ] since limiting literature searching can introduce bias (explored above). Craven et al. have suggested the use of a supporting narrative to explain decisions made in the process of developing literature searches and this advice would usefully capture decisions on the use of search limits [ 75 ].

Key stage five: Determining the process of literature searching and deciding where to search (bibliographic database searching)

Table ​ Table2 2 summarises the process of literature searching as reported in each guidance document. Searching bibliographic databases was consistently reported as the ‘first step’ to literature searching in all nine guidance documents.

Three documents reported specific guidance on where to search, in each case specific to the type of review their guidance informed, and as a minimum requirement [ 4 , 9 , 11 ]. Seven of the key guidance documents suggest that the selection of bibliographic databases depends on the topic of review [ 2 – 4 , 6 – 8 , 10 ], with two documents noting the absence of an agreed standard on what constitutes an acceptable number of databases searched [ 2 , 6 ].

The guidance documents summarise ‘how to’ search bibliographic databases in detail and this guidance is further contextualised above in terms of developing the search strategy. The documents provide guidance of selecting bibliographic databases, in some cases stating acceptable minima (i.e. The Cochrane Handbook states Cochrane CENTRAL, MEDLINE and EMBASE), and in other cases simply listing bibliographic database available to search. Studies have explored the value in searching specific bibliographic databases, with Wright et al. (2015) noting the contribution of CINAHL in identifying qualitative studies [ 76 ], Beckles et al. (2013) questioning the contribution of CINAHL to identifying clinical studies for guideline development [ 77 ], and Cooper et al. (2015) exploring the role of UK-focused bibliographic databases to identify UK-relevant studies [ 78 ]. The host of the database (e.g. OVID or ProQuest) has been shown to alter the search returns offered. Younger and Boddy [ 79 ] report differing search returns from the same database (AMED) but where the ‘host’ was different [ 79 ].

The average number of bibliographic database searched in systematic reviews has risen in the period 1994–2014 (from 1 to 4) [ 80 ] but there remains (as attested to by the guidance) no consensus on what constitutes an acceptable number of databases searched [ 48 ]. This is perhaps because thinking about the number of databases searched is the wrong question, researchers should be focused on which databases were searched and why, and which databases were not searched and why. The discussion should re-orientate to the differential value of sources but researchers need to think about how to report this in studies to allow findings to be generalised. Bethel (2017) has proposed ‘search summaries’, completed by the literature searcher, to record where included studies were identified, whether from database (and which databases specifically) or supplementary search methods [ 81 ]. Search summaries document both yield and accuracy of searches, which could prospectively inform resource use and decisions to search or not to search specific databases in topic areas. The prospective use of such data presupposes, however, that past searches are a potential predictor of future search performance (i.e. that each topic is to be considered representative and not unique). In offering a body of practice, this data would be of greater practicable use than current studies which are considered as little more than individual case studies [ 82 – 90 ].

When to database search is another question posed in the literature. Beyer et al. [ 91 ] report that databases can be prioritised for literature searching which, whilst not addressing the question of which databases to search, may at least bring clarity as to which databases to search first [ 91 ]. Paradoxically, this links to studies that suggest PubMed should be searched in addition to MEDLINE (OVID interface) since this improves the currency of systematic reviews [ 92 , 93 ]. Cooper et al. (2017) have tested the idea of database searching not as a primary search method (as suggested in the guidance) but as a supplementary search method in order to manage the volume of studies identified for an environmental effectiveness systematic review. Their case study compared the effectiveness of database searching versus a protocol using supplementary search methods and found that the latter identified more relevant studies for review than searching bibliographic databases [ 94 ].

Key stage six: Determining the process of literature searching and deciding where to search (supplementary search methods)

Table ​ Table2 2 also summaries the process of literature searching which follows bibliographic database searching. As Table ​ Table2 2 sets out, guidance that supplementary literature search methods should be used in systematic reviews recurs across documents, but the order in which these methods are used, and the extent to which they are used, varies. We noted inconsistency in the labelling of supplementary search methods between guidance documents.

Rather than focus on the guidance on how to use the methods (which has been summarised in a recent review [ 95 ]), we focus on the aim or purpose of supplementary search methods.

The Cochrane Handbook reported that ‘efforts’ to identify unpublished studies should be made [ 9 ]. Four guidance documents [ 2 , 3 , 6 , 9 ] acknowledged that searching beyond bibliographic databases was necessary since ‘databases are not the only source of literature’ [ 2 ]. Only one document reported any guidance on determining when to use supplementary methods. The IQWiG handbook reported that the use of handsearching (in their example) could be determined on a ‘case-by-case basis’ which implies that the use of these methods is optional rather than mandatory. This is in contrast to the guidance (above) on bibliographic database searching.

The issue for supplementary search methods is similar in many ways to the issue of searching bibliographic databases: demonstrating value. The purpose and contribution of supplementary search methods in systematic reviews is increasingly acknowledged [ 37 , 61 , 62 , 96 – 101 ] but understanding the value of the search methods to identify studies and data is unclear. In a recently published review, Cooper et al. (2017) reviewed the literature on supplementary search methods looking to determine the advantages, disadvantages and resource implications of using supplementary search methods [ 95 ]. This review also summarises the key guidance and empirical studies and seeks to address the question on when to use these search methods and when not to [ 95 ]. The guidance is limited in this regard and, as Table ​ Table2 2 demonstrates, offers conflicting advice on the order of searching, and the extent to which these search methods should be used in systematic reviews.

Key stage seven: Managing the references

Five of the documents provided guidance on managing references, for example downloading, de-duplicating and managing the output of literature searches [ 2 , 4 , 6 , 8 , 10 ]. This guidance typically itemised available bibliographic management tools rather than offering guidance on how to use them specifically [ 2 , 4 , 6 , 8 ]. The CEE handbook provided guidance on importing data where no direct export option is available (e.g. web-searching) [ 10 ].

The literature on using bibliographic management tools is not large relative to the number of ‘how to’ videos on platforms such as YouTube (see for example [ 102 ]). These YouTube videos confirm the overall lack of ‘how to’ guidance identified in this study and offer useful instruction on managing references. Bramer et al. set out methods for de-duplicating data and reviewing references in Endnote [ 103 , 104 ] and Gall tests the direct search function within Endnote to access databases such as PubMed, finding a number of limitations [ 105 ]. Coar et al. and Ahmed et al. consider the role of the free-source tool, Zotero [ 106 , 107 ]. Managing references is a key administrative function in the process of review particularly for documenting searches in PRISMA guidance.

Key stage eight: Documenting the search

The Cochrane Handbook was the only guidance document to recommend a specific reporting guideline: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [ 9 ]. Six documents provided guidance on reporting the process of literature searching with specific criteria to report [ 3 , 4 , 6 , 8 – 10 ]. There was consensus on reporting: the databases searched (and the host searched by), the search strategies used, and any use of limits (e.g. date, language, search filters (The CRD handbook called for these limits to be justified [ 6 ])). Three guidance documents reported that the number of studies identified should be recorded [ 3 , 6 , 10 ]. The number of duplicates identified [ 10 ], the screening decisions [ 3 ], a comprehensive list of grey literature sources searched (and full detail for other supplementary search methods) [ 8 ], and an annotation of search terms tested but not used [ 4 ] were identified as unique items in four documents.

The Cochrane Handbook was the only guidance document to note that the full search strategies for each database should be included in the Additional file 1 of the review [ 9 ].

All guidance documents should ultimately deliver completed systematic reviews that fulfil the requirements of the PRISMA reporting guidelines [ 108 ]. The guidance broadly requires the reporting of data that corresponds with the requirements of the PRISMA statement although documents typically ask for diverse and additional items [ 108 ]. In 2008, Sampson et al. observed a lack of consensus on reporting search methods in systematic reviews [ 109 ] and this remains the case as of 2017, as evidenced in the guidance documents, and in spite of the publication of the PRISMA guidelines in 2009 [ 110 ]. It is unclear why the collective guidance does not more explicitly endorse adherence to the PRISMA guidance.

Reporting of literature searching is a key area in systematic reviews since it sets out clearly what was done and how the conclusions of the review can be believed [ 52 , 109 ]. Despite strong endorsement in the guidance documents, specifically supported in PRISMA guidance, and other related reporting standards too (such as ENTREQ for qualitative evidence synthesis, STROBE for reviews of observational studies), authors still highlight the prevalence of poor standards of literature search reporting [ 31 , 110 – 119 ]. To explore issues experienced by authors in reporting literature searches, and look at uptake of PRISMA, Radar et al. [ 120 ] surveyed over 260 review authors to determine common problems and their work summaries the practical aspects of reporting literature searching [ 120 ]. Atkinson et al. [ 121 ] have also analysed reporting standards for literature searching, summarising recommendations and gaps for reporting search strategies [ 121 ].

One area that is less well covered by the guidance, but nevertheless appears in this literature, is the quality appraisal or peer review of literature search strategies. The PRESS checklist is the most prominent and it aims to develop evidence-based guidelines to peer review of electronic search strategies [ 5 , 122 , 123 ]. A corresponding guideline for documentation of supplementary search methods does not yet exist although this idea is currently being explored.

How the reporting of the literature searching process corresponds to critical appraisal tools is an area for further research. In the survey undertaken by Radar et al. (2014), 86% of survey respondents (153/178) identified a need for further guidance on what aspects of the literature search process to report [ 120 ]. The PRISMA statement offers a brief summary of what to report but little practical guidance on how to report it [ 108 ]. Critical appraisal tools for systematic reviews, such as AMSTAR 2 (Shea et al. [ 124 ]) and ROBIS (Whiting et al. [ 125 ]), can usefully be read alongside PRISMA guidance, since they offer greater detail on how the reporting of the literature search will be appraised and, therefore, they offer a proxy on what to report [ 124 , 125 ]. Further research in the form of a study which undertakes a comparison between PRISMA and quality appraisal checklists for systematic reviews would seem to begin addressing the call, identified by Radar et al., for further guidance on what to report [ 120 ].

Limitations

Other handbooks exist.

A potential limitation of this literature review is the focus on guidance produced in Europe (the UK specifically) and Australia. We justify the decision for our selection of the nine guidance documents reviewed in this literature review in section “ Identifying guidance ”. In brief, these nine guidance documents were selected as the most relevant health care guidance that inform UK systematic reviewing practice, given that the UK occupies a prominent position in the science of health information retrieval. We acknowledge the existence of other guidance documents, such as those from North America (e.g. the Agency for Healthcare Research and Quality (AHRQ) [ 126 ], The Institute of Medicine [ 127 ] and the guidance and resources produced by the Canadian Agency for Drugs and Technologies in Health (CADTH) [ 128 ]). We comment further on this directly below.

The handbooks are potentially linked to one another

What is not clear is the extent to which the guidance documents inter-relate or provide guidance uniquely. The Cochrane Handbook, first published in 1994, is notably a key source of reference in guidance and systematic reviews beyond Cochrane reviews. It is not clear to what extent broadening the sample of guidance handbooks to include North American handbooks, and guidance handbooks from other relevant countries too, would alter the findings of this literature review or develop further support for the process model. Since we cannot be clear, we raise this as a potential limitation of this literature review. On our initial review of a sample of North American, and other, guidance documents (before selecting the guidance documents considered in this review), however, we do not consider that the inclusion of these further handbooks would alter significantly the findings of this literature review.

This is a literature review

A further limitation of this review was that the review of published studies is not a systematic review of the evidence for each key stage. It is possible that other relevant studies could help contribute to the exploration and development of the key stages identified in this review.

This literature review would appear to demonstrate the existence of a shared model of the literature searching process in systematic reviews. We call this model ‘the conventional approach’, since it appears to be common convention in nine different guidance documents.

The findings reported above reveal eight key stages in the process of literature searching for systematic reviews. These key stages are consistently reported in the nine guidance documents which suggests consensus on the key stages of literature searching, and therefore the process of literature searching as a whole, in systematic reviews.

In Table ​ Table2, 2 , we demonstrate consensus regarding the application of literature search methods. All guidance documents distinguish between primary and supplementary search methods. Bibliographic database searching is consistently the first method of literature searching referenced in each guidance document. Whilst the guidance uniformly supports the use of supplementary search methods, there is little evidence for a consistent process with diverse guidance across documents. This may reflect differences in the core focus across each document, linked to differences in identifying effectiveness studies or qualitative studies, for instance.

Eight of the nine guidance documents reported on the aims of literature searching. The shared understanding was that literature searching should be thorough and comprehensive in its aim and that this process should be reported transparently so that that it could be reproduced. Whilst only three documents explicitly link this understanding to minimising bias, it is clear that comprehensive literature searching is implicitly linked to ‘not missing relevant studies’ which is approximately the same point.

Defining the key stages in this review helps categorise the scholarship available, and it prioritises areas for development or further study. The supporting studies on preparing for literature searching (key stage three, ‘preparation’) were, for example, comparatively few, and yet this key stage represents a decisive moment in literature searching for systematic reviews. It is where search strategy structure is determined, search terms are chosen or discarded, and the resources to be searched are selected. Information specialists, librarians and researchers, are well placed to develop these and other areas within the key stages we identify.

This review calls for further research to determine the suitability of using the conventional approach. The publication dates of the guidance documents which underpin the conventional approach may raise questions as to whether the process which they each report remains valid for current systematic literature searching. In addition, it may be useful to test whether it is desirable to use the same process model of literature searching for qualitative evidence synthesis as that for reviews of intervention effectiveness, which this literature review demonstrates is presently recommended best practice.

Additional file

Appendix tables and PubMed search strategy. Key studies used for pearl growing per key stage, working data extraction tables and the PubMed search strategy. (DOCX 30 kb)

Acknowledgements

CC acknowledges the supervision offered by Professor Chris Hyde.

This publication forms a part of CC’s PhD. CC’s PhD was funded through the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme (Project Number 16/54/11). The open access fee for this publication was paid for by Exeter Medical School.

RG and NB were partially supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care South West Peninsula.

The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.

Abbreviations

Authors’ contributions.

CC conceived the idea for this study and wrote the first draft of the manuscript. CC discussed this publication in PhD supervision with AB and separately with JVC. CC revised the publication with input and comments from AB, JVC, RG and NB. All authors revised the manuscript prior to submission. All authors read and approved the final manuscript.

Ethics approval and consent to participate

Consent for publication, competing interests.

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Contributor Information

Chris Cooper, Email: [email protected] .

Andrew Booth, Email: [email protected] .

Jo Varley-Campbell, Email: [email protected] .

Nicky Britten, Email: [email protected] .

Ruth Garside, Email: [email protected] .

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What is a Literature Review?

What’s a literature review.

The straightforward answer is that a literature review is a review or synthesis of all the research published on a certain topic. But I’d rather explain it from a skateboarder’s perspective:

One of my favorite movies is the 1989 classic Back to the Future Part 2 where the bodacious skater Marty McFly time-travels to the future and sees a hoverboard. As a kid, I was a dabbling skateboarder and thought if I could just have one of those hoverboards, all my troubles would disappear. It was an optimistic time.

Trouble is, hoverboards are really hard to make. We’ve already passed the year 2015 when the “Future” of Back to the Future Part 2 takes place, and guess what? No hoverboards. I know you’ve seen a skateboard-like, two-wheeled device marketed with the name “Hoverboard” but that’s just an electric, no-handled scooter.

1024px-Hover_board_hovering.jpg

I want a real hoverboard. That you ride in the air . So how can we know when real hoverboards will be available? How can we know where the technology is now? Will we know a real hoverboard when we see one? Tony Hawk, the best skateboarder of all time (whose face was incidentally taped to my wall in the ’80s) recently filmed a 2-minute video of how far real hoverboard technology has come–filmed on the very day Marty McFly supposedly went to the future: October 21, 2015:

Tony Hawk and the cutting edge of hoverboard research

Image preview of a YouTube video

Although this “hoverboard” was really a huge black rectangle the size of Delaware floating only an inch off the ground, and although Tony Hawk fell off a lot, he was technically in the air, so I’m taking that as a good sign. Then recently, a professional jet ski rider broke the world record for longest time “hovering” in the air with a highly dangerous jet-engine-propelled contraption called Flyboard Air. It’s also definitely a step in the right direction, but there’s a big problem (beside extreme danger): it’s projected to cost around $250,000.

The good news is, now we’ve found the point where hoverboard research actually is. The bad news: we have to face the sad truth that it might still be a while before we get real flying hoverboards. But at least now we know.

The State of a Field on a Topic

That leads me to literature reviews. Whenever you want to know the state of a field of research like how far hoverboard technology has come, the best way to find out is probably not YouTube videos. It turns out you can do something much more reliable: conduct a literature review . In this case, “literature” doesn’t mean the Victorian novels you read in English class, it means all the research published on a certain topic. So a literature review is simply a review or a synthesis of the research published on a topic.

Researchers today don’t just start projects out of the blue–they do their homework first by finding out what others have already researched. So if you want to make a hoverboard, you don’t just go to Home Depot and buy random parts–you research what others have done and check out the conversation so you don’t have to reinvent the wheel.

“If I have seen further, it is by standing on the shoulders of giants.” –Sir Isaac Newton (and the motto of Google Scholar)

Before good researchers set up any surveys or experiments, or even write a proposal for funding, they figure out exactly which research questions have already been asked and answered. Same goes for anyone wanting to make a product that will sell. But more importantly, they look for the gaps in the research where answers have yet to be found. And then they focus their own research on filling in some of those gaps. That’ll be your job, too.

In other words, the goal of a literature review is to find the sweet spot where the most promising research is happening now–we call that the cutting edge.

How is a Literature Review different from a typical Research Paper?

You’ve probably been writing research papers most of your life– starting from the five-paragraph essay you learned in high school to the term paper you wrote last semester that had a thesis statement and lots of quotes. So it can seem daunting to switch gears to writing a literature review, but there are some distinct advantages to making the switch. The trick is first understanding the difference between the two.

Research Papers are Thesis Driven

The difference between a typical research paper and a literature review is your purpose and strategy. When you’re assigned to write a research paper, you start with a thesis or argument that you’d like to make. Your thesis has to do with changes you’d like to see in the future. Then you search for sources that support your point. You might adjust your thesis if you come across sources that challenge your claim, but generally, the sources you’ve gathered become evidence for your thesis and you use them to support your point. In other words, your argumentative research paper is driven by your thesis .

Literature Reviews are Source Driven

In contrast, when you write a Literature Review, the sources themselves dictate what you’ll say in your paper. Remember, your goal is to tell your audience the state of the field on a topic–what’s been happening in the published research–so you can find the cutting edge and where the research gaps are. Therefore, you need to find and evaluate the most relevant sources surrounding a topic and then write a review based on what you find . You can’t decide on a thesis statement or know what points you’ll make before you start because you have to find out what researchers are doing before you can report on that. Simply put, your literature review is driven by your sources .

You’ll still have an overarching point/thesis that controls your literature review paper structure, but it will be a claim about what patterns you found in the research– not an argument about a change you want to see in the future or a new way to look at something. And you’ll decide on your thesis much later in the writing process. Here’s a table that compares the writing process of a traditional research paper with that of a literature review:

Literature Reviews: Catching up with Old Friends

What do you do when you meet an old friend? You ask,

“How are you? What have you been up to? Fill me in!”

people-talking-908342_1280.jpg

Literature Reviews are like getting filled in by an old friend . Only this time, you’re explaining how a field of research has gotten to the present (like how far hoverboard technology has come). But like a conversation with an old friend, you want to review only the details most relevant to the situation. You don’t usually give a moment-by-moment chronology of what you’ve done in your life (no one has time for that); rather, you talk in terms of categories–work, family, travel, etc. This is like the synthesis that happens in a Literature Review. As you read sources about a specific topic, you’ll look for themes, for similarities and differences, for points of agreement and disagreement, for gaps in the research that haven’t been filled in yet. Those themes become the categories you’ll talk about in your literature review so your audience will understand the big picture about your topic.

Literature Reviews in the Sciences

Grant proposals.

Any grant proposal submitted to request research funding begins with an extensive literature review to justify the need for the research funds. If you can prove there’s a gap in knowledge, it makes it that much easier to convince your audience to give you funding to fill that gap.

IMRAD Articles

Wineglass_model_for_IMRaD_structure..png

The Introduction of an IMRAD article includes a literature review. Photo by Tom Toyosak i on Wikimedia Commons

IMRAD (pronounced “im-rad”) stands for Introduction, Methods, Results, and Discussion and is the most common genre published in the social sciences and sciences. Most of the sources you gather will likely be IMRAD-format papers. The I in IMRAD stands for Introduction and usually consists of a review of the literature on the authors’ research topic. The author(s) usually use the Introduction section to report on the published literature about their research topic and reveal the trends and gaps in current research. An added benefit to beginning an article this way is that by showing the gaps in the research, the author(s) can justify their own research and explain the significance of the topic they chose to examine. Clever!

As you might guess, the sections following the Introduction (Methods, Results, Discussion) describe the primary research the author(s) conducted to answer their research question. First they report on their quantitative and/or qualitative M ethods (M in IMRAD) including statistical analyses. Then they publish their R esults (R in IMRAD). Finally, the author(s) embark on a D iscussion (D in IMRAD) of their results in the context of the greater field of research and make suggestions for future research. This starts the research cycle over again as someone else reads their article as part of their own review of the literature and discovers a gap in the research that can be filled by new primary research. 

Published Literature Reviews

In the world of science and social science, literature reviews can also be published on their own. For example, if someone does an extensive investigation into an important topic, the publishers of academic journals will often publish that literature review on its own to help other researchers understand that topic better.

Popular Literature Reviews

196px-Wikipedia-logo-en-big.png

Lest you think nerdy academics are the only ones who rely on literature reviews, recall the last time you went on Wikipedia . If you think about it, Wikipedia is really just a giant literature review on millions of topics. Although the information on Wikipedia is not formally peer-reviewed like the reviews published in academic journals, they do cite all their sources and frequently revise to keep the information current. Clearly there’s a market for relevant information. If you really want your mind to explode Inception -style, look up “Wikipedia” on Wikipedia and you’ll find a literature review about a literature review.

Adapted from “What is a Literature Review?” in Writing in the Social Sciences. Authored by Christie Cowles Charles. Located at: https://edtechbooks.org/writing.

License: CC BY- SA

What is a Literature Review? Copyright © 2020 by Sara Rufner is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

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2: Overview of the Scientific Method

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  • Page ID 20140

  • Rajiv S. Jhangiani, I-Chant A. Chiang, Carrie Cuttler, & Dana C. Leighton
  • Kwantlen Polytechnic U., Washington State U., & Texas A&M U.—Texarkana

In this chapter, we give you a broad overview of the various stages of the research process. These include finding a topic of investigation, reviewing the literature, refining your research question and generating a hypothesis, designing and conducting a study, analyzing the data, coming to conclusions, and reporting the results.

  • 2.1: Prelude to the Scientific Method Taking notes on laptops rather than in longhand is increasingly common. Many researchers have suggested that laptop note taking is less effective than longhand note taking for learning. Prior studies have primarily focused on students’ capacity for multitasking and distraction when using laptops. The present research suggests that even when laptops are used solely to take notes, they may still be impairing learning because their use results in shallower processing.
  • 2.2: A Model of Scientific Research in Psychology The researcher formulates a research question, conducts a study designed to answer the question, analyzes the resulting data, draws conclusions about the answer to the question, and publishes the results so that they become part of the research literature. Because the research literature is one of the primary sources of new research questions, this process can be thought of as a cycle. New research leads to new questions, which lead to new research, and so on.
  • 2.3: Finding a Research Topic Good research must begin with a good research question. Yet coming up with good research questions is something that novice researchers often find difficult and stressful. One reason is that this is a creative process that can appear mysterious—even magical—with experienced researchers seeming to pull interesting research questions out of thin air. However, psychological research on creativity has shown that it is neither as mysterious nor as magical as it appears.
  • 2.4: Generating Good Research Questions Once you have a research idea, you need to use it to generate one or more empirically testable research questions, that is, questions expressed in terms of a single variable or relationship between variables. One way to do this is to look closely at the discussion section in a recent research article on the topic. This is the last major section of the article, in which the researchers summarize their results, interpret them in the context of past research, and suggest directions for research.
  • 2.5: Developing a Hypothesis A theory is a coherent explanation or interpretation of one or more phenomena. Although theories can take a variety of forms, one thing they have in common is that they go beyond the phenomena they explain by including variables, structures, processes, functions, or organizing principles that have not been observed directly. A hypothesis, on the other hand, is a specific prediction about a new phenomenon that should be observed if a particular theory is accurate.
  • 2.6: Designing a Research Study Part of generating a hypothesis involves identifying the variables that you want to study and operationally defining those variables so that they can be measured. Research questions in psychology are about variables. A variable is a quantity or quality that varies across people or situations. For example, the height of the students enrolled in a university course is a variable because it varies from student to student.
  • 2.7: Analyzing the Data Once the study is complete and the observations have been made and recorded the researchers need to analyze the data and draw their conclusions. Typically, data are analyzed using both descriptive and inferential statistics. Descriptive statistics are used to summarize the data and inferential statistics are used to generalize the results from the sample to the population.
  • 2.8: Drawing Conclusions and Reporting the Results Since statistics are probabilistic in nature and findings can reflect type I or type II errors, we cannot use the results of a single study to conclude with certainty that a theory is true. Rather theories are supported, refuted, or modified based on the results of research. If the results are statistically significant and consistent with the hypothesis and the theory that was used to generate the hypothesis, then researchers can conclude that the theory is supported.
  • 2.9: Overview of the Scientific Method (Summary) Key Takeaways and Exercises for the chapter on Overview of the Scientific Method.

IMAGES

  1. Formula for Using the Scientific Method

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  2. The scientific method is a process for experimentation

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  3. Scientific Method: Definition and Examples

    literature review as a step in the scientific method entails

  4. Steps of the Scientific Method

    literature review as a step in the scientific method entails

  5. Literature Review: What is and How to do it?

    literature review as a step in the scientific method entails

  6. Scientific Method

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  1. Chapter two

  2. How to Write a Literature Review a short Step by step Guide

  3. What is literature review?

  4. Approaches to Literature Review

  5. HOW TO WRITE A LITERATURE REVIEW; A Step-by-Step Guide to writing a Literature Review

  6. How to do literature review II Blessed my content was useful 👏👍😊 #phdadmission #bhu

COMMENTS

  1. How to 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.

  2. Literature review as a research methodology: An ...

    In these cases, a literature review provides the basis for building a new conceptual model or theory, and it can be valuable when aiming to map the development of a particular research field over time. However, it is important to note that depending on the goal of the literature review, the method that should be used will vary. 2.1.

  3. Steps in Conducting 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.

  4. Chapter 9 Methods for Literature Reviews

    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 ...

  5. Literature Review

    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 ...

  6. Writing a Literature Review

    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).

  7. 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.

  8. Methodological Approaches to Literature Review

    A literature review is defined as "a critical analysis of a segment of a published body of knowledge through summary, classification, and comparison of prior research studies, reviews of literature, and theoretical articles." (The Writing Center University of Winconsin-Madison 2022) A literature review is an integrated analysis, not just a summary of scholarly work on a specific topic.

  9. How to write a superb literature review

    The best proposals are timely and clearly explain why readers should pay attention to the proposed topic. It is not enough for a review to be a summary of the latest growth in the literature: the ...

  10. How-to conduct a systematic literature review: A quick guide for

    Abstract. Performing a literature review is a critical first step in research to understanding the state-of-the-art and identifying gaps and challenges in the field. A systematic literature review is a method which sets out a series of steps to methodically organize the review. In this paper, we present a guide designed for researchers and in ...

  11. Writing a Literature Review

    A literature review is structured differently from an original research article. It is developed based on themes, rather than stages of the scientific method. In the article Ten simple rules for writing a literature review, Marco Pautasso explains the importance of literature reviews: Literature reviews are in great demand in most scientific ...

  12. PDF CHAPTER 3 Conducting a Literature Review

    purpose of a literature review, people are better able to accom-plish them. Third, what a literature entails is rarely explicated. Too frequently, someone is expected to write a literature review when what is involved in constructing a literature review has not been explained to them. Fourth, clearly outlining the steps

  13. Methods and the Literature Review

    This book includes steps for students and experienced scholars, with discussion of a variety of literature review types. Conducting research literature reviews:From the Internet to Paper (Fink, 2019). Available resources include Chapters 1 and 2. This edition includes recommendations for organizing literature reviews using online resources.

  14. Ten Simple Rules for Writing a Literature Review

    Literature reviews are in great demand in most scientific fields. Their need stems from the ever-increasing output of scientific publications .For example, compared to 1991, in 2008 three, eight, and forty times more papers were indexed in Web of Science on malaria, obesity, and biodiversity, respectively .Given such mountains of papers, scientists cannot be expected to examine in detail every ...

  15. Literature Reviews: Modern Methods for Investigating Scientific and

    Literature Reviews describes an innovative system for creating systematic literature reviews, through reviewing, analyzing, and synthesizing scientific and technological literature. It then discusses systematic literature reviews, content analysis, and literature synthesis separately, before presenting the methodology to combine them in one ...

  16. Steps in the Literature Review Process

    Literature Review and Research Design by Dave Harris This book looks at literature review in the process of research design, and how to develop a research practice that will build skills in reading and writing about research literature--skills that remain valuable in both academic and professional careers. Literature review is approached as a process of engaging with the discourse of scholarly ...

  17. Description of the Systematic Literature Review Method

    A systematic literature review (SLR) is an independent academic method that aims to identify and evaluate all relevant literature on a topic in order to derive conclusions about the question under consideration. "Systematic reviews are undertaken to clarify the state of existing research and the implications that should be drawn from this."

  18. 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 ...

  19. 5.4: The Scientific Method

    The first step of the scientific method is to ask a question, describe a problem, and identify the specific area of interest. ... The next step researchers undertake is to conduct background research through a literature review, which is a review of any existing similar or related studies. A visit to the library or a thorough online search of ...

  20. Introduction to Systematic Reviews

    As the scientific literature continues to grow, an immense amount of time and effort is needed to generate high-quality, comprehensive systematic reviews. While the time needed to produce a review can be quite variable, estimates range from 6 months when an investigator devotes 10-20 h per week (Whitaker 2015 ) to, on average, 16 months ...

  21. Defining the process to literature searching in systematic reviews: a

    Background. Systematic literature searching is recognised as a critical component of the systematic review process. It involves a systematic search for studies and aims for a transparent report of study identification, leaving readers clear about what was done to identify studies, and how the findings of the review are situated in the relevant evidence.

  22. What is a Literature Review?

    Literature Reviews are Source Driven. In contrast, when you write a Literature Review, the sources themselves dictate what you'll say in your paper. Remember, your goal is to tell your audience the state of the field on a topic-what's been happening in the published research-so you can find the cutting edge and where the research gaps are.

  23. 2: Overview of the Scientific Method

    These include finding a topic of investigation, reviewing the literature, refining your research question and generating a hypothesis, designing and conducting a study, analyzing the data, coming to conclusions, and reporting the results. 2.1: Prelude to the Scientific Method. Taking notes on laptops rather than in longhand is increasingly common.