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Writing a Literature Review

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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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Ten Simple Rules for Writing a Literature Review

Marco pautasso.

1 Centre for Functional and Evolutionary Ecology (CEFE), CNRS, Montpellier, France

2 Centre for Biodiversity Synthesis and Analysis (CESAB), FRB, Aix-en-Provence, France

Literature reviews are in great demand in most scientific fields. Their need stems from the ever-increasing output of scientific publications [1] . 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 [2] . Given such mountains of papers, scientists cannot be expected to examine in detail every single new paper relevant to their interests [3] . 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 [4] . For such summaries to be useful, however, they need to be compiled in a professional way [5] .

When starting from scratch, reviewing the literature can require a titanic amount of work. That is why researchers who have spent their career working on a certain research issue are in a perfect position to review that literature. Some graduate schools are now offering courses in reviewing the literature, given that most research students start their project by producing an overview of what has already been done on their research issue [6] . However, it is likely that most scientists have not thought in detail about how to approach and carry out a literature review.

Reviewing the literature requires the ability to juggle multiple tasks, from finding and evaluating relevant material to synthesising information from various sources, from critical thinking to paraphrasing, evaluating, and citation skills [7] . In this contribution, I share ten simple rules I learned working on about 25 literature reviews as a PhD and postdoctoral student. Ideas and insights also come from discussions with coauthors and colleagues, as well as feedback from reviewers and editors.

Rule 1: Define a Topic and Audience

How to choose which topic to review? There are so many issues in contemporary science that you could spend a lifetime of attending conferences and reading the literature just pondering what to review. On the one hand, if you take several years to choose, several other people may have had the same idea in the meantime. On the other hand, only a well-considered topic is likely to lead to a brilliant literature review [8] . The topic must at least be:

• interesting to you (ideally, you should have come across a series of recent papers related to your line of work that call for a critical summary),
• an important aspect of the field (so that many readers will be interested in the review and there will be enough material to write it), and
• a well-defined issue (otherwise you could potentially include thousands of publications, which would make the review unhelpful).

Ideas for potential reviews may come from papers providing lists of key research questions to be answered [9] , but also from serendipitous moments during desultory reading and discussions. In addition to choosing your topic, you should also select a target audience. In many cases, the topic (e.g., web services in computational biology) will automatically define an audience (e.g., computational biologists), but that same topic may also be of interest to neighbouring fields (e.g., computer science, biology, etc.).

Rule 2: Search and Re-search the Literature

After having chosen your topic and audience, start by checking the literature and downloading relevant papers. Five pieces of advice here:

• keep track of the search items you use (so that your search can be replicated [10] ),
• keep a list of papers whose pdfs you cannot access immediately (so as to retrieve them later with alternative strategies),
• use a paper management system (e.g., Mendeley, Papers, Qiqqa, Sente),
• define early in the process some criteria for exclusion of irrelevant papers (these criteria can then be described in the review to help define its scope), and
• do not just look for research papers in the area you wish to review, but also seek previous reviews.

The chances are high that someone will already have published a literature review ( Figure 1 ), if not exactly on the issue you are planning to tackle, at least on a related topic. If there are already a few or several reviews of the literature on your issue, my advice is not to give up, but to carry on with your own literature review,

The bottom-right situation (many literature reviews but few research papers) is not just a theoretical situation; it applies, for example, to the study of the impacts of climate change on plant diseases, where there appear to be more literature reviews than research studies [33] .

• discussing in your review the approaches, limitations, and conclusions of past reviews,
• trying to find a new angle that has not been covered adequately in the previous reviews, and
• incorporating new material that has inevitably accumulated since their appearance.

When searching the literature for pertinent papers and reviews, the usual rules apply:

• be thorough,
• use different keywords and database sources (e.g., DBLP, Google Scholar, ISI Proceedings, JSTOR Search, Medline, Scopus, Web of Science), and
• look at who has cited past relevant papers and book chapters.

Rule 3: Take Notes While Reading

If you read the papers first, and only afterwards start writing the review, you will need a very good memory to remember who wrote what, and what your impressions and associations were while reading each single paper. My advice is, while reading, to start writing down interesting pieces of information, insights about how to organize the review, and thoughts on what to write. This way, by the time you have read the literature you selected, you will already have a rough draft of the review.

Of course, this draft will still need much rewriting, restructuring, and rethinking to obtain a text with a coherent argument [11] , but you will have avoided the danger posed by staring at a blank document. Be careful when taking notes to use quotation marks if you are provisionally copying verbatim from the literature. It is advisable then to reformulate such quotes with your own words in the final draft. It is important to be careful in noting the references already at this stage, so as to avoid misattributions. Using referencing software from the very beginning of your endeavour will save you time.

Rule 4: Choose the Type of Review You Wish to Write

After having taken notes while reading the literature, you will have a rough idea of the amount of material available for the review. This is probably a good time to decide whether to go for a mini- or a full review. Some journals are now favouring the publication of rather short reviews focusing on the last few years, with a limit on the number of words and citations. A mini-review is not necessarily a minor review: it may well attract more attention from busy readers, although it will inevitably simplify some issues and leave out some relevant material due to space limitations. A full review will have the advantage of more freedom to cover in detail the complexities of a particular scientific development, but may then be left in the pile of the very important papers “to be read” by readers with little time to spare for major monographs.

There is probably a continuum between mini- and full reviews. The same point applies to the dichotomy of descriptive vs. integrative reviews. While descriptive reviews focus on the methodology, findings, and interpretation of each reviewed study, integrative reviews attempt to find common ideas and concepts from the reviewed material [12] . A similar distinction exists between narrative and systematic reviews: while narrative reviews are qualitative, systematic reviews attempt to test a hypothesis based on the published evidence, which is gathered using a predefined protocol to reduce bias [13] , [14] . When systematic reviews analyse quantitative results in a quantitative way, they become meta-analyses. The choice between different review types will have to be made on a case-by-case basis, depending not just on the nature of the material found and the preferences of the target journal(s), but also on the time available to write the review and the number of coauthors [15] .

Rule 5: Keep the Review Focused, but Make It of Broad Interest

Whether your plan is to write a mini- or a full review, it is good advice to keep it focused 16 , 17 . Including material just for the sake of it can easily lead to reviews that are trying to do too many things at once. The need to keep a review focused can be problematic for interdisciplinary reviews, where the aim is to bridge the gap between fields [18] . If you are writing a review on, for example, how epidemiological approaches are used in modelling the spread of ideas, you may be inclined to include material from both parent fields, epidemiology and the study of cultural diffusion. This may be necessary to some extent, but in this case a focused review would only deal in detail with those studies at the interface between epidemiology and the spread of ideas.

While focus is an important feature of a successful review, this requirement has to be balanced with the need to make the review relevant to a broad audience. This square may be circled by discussing the wider implications of the reviewed topic for other disciplines.

Rule 6: Be Critical and Consistent

Reviewing the literature is not stamp collecting. A good review does not just summarize the literature, but discusses it critically, identifies methodological problems, and points out research gaps [19] . After having read a review of the literature, a reader should have a rough idea of:

• the major achievements in the reviewed field,
• the main areas of debate, and
• the outstanding research questions.

It is challenging to achieve a successful review on all these fronts. A solution can be to involve a set of complementary coauthors: some people are excellent at mapping what has been achieved, some others are very good at identifying dark clouds on the horizon, and some have instead a knack at predicting where solutions are going to come from. If your journal club has exactly this sort of team, then you should definitely write a review of the literature! In addition to critical thinking, a literature review needs consistency, for example in the choice of passive vs. active voice and present vs. past tense.

Rule 7: Find a Logical Structure

Like a well-baked cake, a good review has a number of telling features: it is worth the reader's time, timely, systematic, well written, focused, and critical. It also needs a good structure. With reviews, the usual subdivision of research papers into introduction, methods, results, and discussion does not work or is rarely used. However, a general introduction of the context and, toward the end, a recapitulation of the main points covered and take-home messages make sense also in the case of reviews. For systematic reviews, there is a trend towards including information about how the literature was searched (database, keywords, time limits) [20] .

How can you organize the flow of the main body of the review so that the reader will be drawn into and guided through it? It is generally helpful to draw a conceptual scheme of the review, e.g., with mind-mapping techniques. Such diagrams can help recognize a logical way to order and link the various sections of a review [21] . This is the case not just at the writing stage, but also for readers if the diagram is included in the review as a figure. A careful selection of diagrams and figures relevant to the reviewed topic can be very helpful to structure the text too [22] .

Rule 8: Make Use of Feedback

Reviews of the literature are normally peer-reviewed in the same way as research papers, and rightly so [23] . As a rule, incorporating feedback from reviewers greatly helps improve a review draft. Having read the review with a fresh mind, reviewers may spot inaccuracies, inconsistencies, and ambiguities that had not been noticed by the writers due to rereading the typescript too many times. It is however advisable to reread the draft one more time before submission, as a last-minute correction of typos, leaps, and muddled sentences may enable the reviewers to focus on providing advice on the content rather than the form.

Feedback is vital to writing a good review, and should be sought from a variety of colleagues, so as to obtain a diversity of views on the draft. This may lead in some cases to conflicting views on the merits of the paper, and on how to improve it, but such a situation is better than the absence of feedback. A diversity of feedback perspectives on a literature review can help identify where the consensus view stands in the landscape of the current scientific understanding of an issue [24] .

Rule 9: Include Your Own Relevant Research, but Be Objective

In many cases, reviewers of the literature will have published studies relevant to the review they are writing. This could create a conflict of interest: how can reviewers report objectively on their own work [25] ? Some scientists may be overly enthusiastic about what they have published, and thus risk giving too much importance to their own findings in the review. However, bias could also occur in the other direction: some scientists may be unduly dismissive of their own achievements, so that they will tend to downplay their contribution (if any) to a field when reviewing it.

In general, a review of the literature should neither be a public relations brochure nor an exercise in competitive self-denial. If a reviewer is up to the job of producing a well-organized and methodical review, which flows well and provides a service to the readership, then it should be possible to be objective in reviewing one's own relevant findings. In reviews written by multiple authors, this may be achieved by assigning the review of the results of a coauthor to different coauthors.

Rule 10: Be Up-to-Date, but Do Not Forget Older Studies

Given the progressive acceleration in the publication of scientific papers, today's reviews of the literature need awareness not just of the overall direction and achievements of a field of inquiry, but also of the latest studies, so as not to become out-of-date before they have been published. Ideally, a literature review should not identify as a major research gap an issue that has just been addressed in a series of papers in press (the same applies, of course, to older, overlooked studies (“sleeping beauties” [26] )). This implies that literature reviewers would do well to keep an eye on electronic lists of papers in press, given that it can take months before these appear in scientific databases. Some reviews declare that they have scanned the literature up to a certain point in time, but given that peer review can be a rather lengthy process, a full search for newly appeared literature at the revision stage may be worthwhile. Assessing the contribution of papers that have just appeared is particularly challenging, because there is little perspective with which to gauge their significance and impact on further research and society.

Inevitably, new papers on the reviewed topic (including independently written literature reviews) will appear from all quarters after the review has been published, so that there may soon be the need for an updated review. But this is the nature of science [27] – [32] . I wish everybody good luck with writing a review of the literature.

Acknowledgments

Many thanks to M. Barbosa, K. Dehnen-Schmutz, T. Döring, D. Fontaneto, M. Garbelotto, O. Holdenrieder, M. Jeger, D. Lonsdale, A. MacLeod, P. Mills, M. Moslonka-Lefebvre, G. Stancanelli, P. Weisberg, and X. Xu for insights and discussions, and to P. Bourne, T. Matoni, and D. Smith for helpful comments on a previous draft.

Funding Statement

This work was funded by the French Foundation for Research on Biodiversity (FRB) through its Centre for Synthesis and Analysis of Biodiversity data (CESAB), as part of the NETSEED research project. The funders had no role in the preparation of the manuscript.

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

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

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

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

There are five key steps to writing a literature review:

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

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

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Table of contents

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

• Quick Run-through
• Step 1 & 2

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

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

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

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

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

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

Download Word doc Download Google doc

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

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

Make a list of keywords

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

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

Search for relevant sources

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

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

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

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

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

For each publication, ask yourself:

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

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

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

Take notes and cite your sources

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

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

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

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

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

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

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

Chronological

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

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

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

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

Methodological

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

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

Theoretical

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

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

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

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

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

As you write, you can follow these tips:

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

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

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

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

Scribbr slides are free to use, customize, and distribute for educational purposes.

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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.

• Sampling methods
• Simple random sampling
• Stratified sampling
• Cluster sampling
• Likert scales
• Reproducibility

 Statistics

• Null hypothesis
• Statistical power
• Probability distribution
• Effect size
• Poisson distribution

Research bias

• Optimism bias
• Cognitive bias
• Implicit bias
• Hawthorne effect
• Anchoring bias
• Explicit bias

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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Literature Reviews

• Getting started

What is a literature review?

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

• Types of reviews
• 1. Define your research question
• 2. Plan your search
• 3. Search the literature
• 4. Organize your results
• 5. Synthesize your findings
• 6. Write the review
• Artificial intelligence (AI) tools
• Thompson Writing Studio This link opens in a new window
• Need to write a systematic review? This link opens in a new window

Guide Owner

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Definition: A literature review is a systematic examination and synthesis of existing scholarly research on a specific topic or subject.

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

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

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

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

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

What is a literature review NOT?

❌ An annotated bibliography

❌ Original research

❌ A summary

❌ Something to be conducted at the end of your research

❌ An opinion piece

❌ A chronological compilation of studies

The reason for conducting a literature review is to:

Literature Reviews: An Overview for Graduate Students

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

Writing the literature review: A practical guide

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

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Telling a research story: Writing a literature review

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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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APA Style Blog - for those harder to find answers

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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What is a literature review?

Conducting a literature review, organizing a literature review, writing a literature review, helpful book.

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A  literature review  is a compilation of the works published in a particular field of study or line of research, usually over a specific period of time, in the form of an in-depth, critical bibliographic essay or annotated list in which attention is drawn to the most significant works.

• Summarizes and analyzes previous research relevant to a topic
• Includes scholarly books and articles published in academic journals
• Can be an specific scholarly paper or a section in a research paper

The objective of a Literature Review is to find previous published scholarly works relevant to an specific topic

• Help gather ideas or information
• Keep up to date in current trends and findings
• Help develop new questions

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
• Helps focus your own research questions or problems
• Discovers relationships between research studies/ideas
• Suggests unexplored ideas or populations
• Identifies major themes, concepts, and researchers on a topic
• Tests assumptions; may help counter preconceived ideas and remove unconscious bias
• Identifies critical gaps, points of disagreement, or potentially flawed methodology or theoretical approaches

Source: "What is a Literature Review?", Old Dominion University,  https://guides.lib.odu.edu/c.php?g=966167&p=6980532

1. Choose a topic. Define your research question. 

Your literature review should be guided by a central research question. It 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.
• Write down terms that are related to your question for they will be useful for searches later. 

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.
• Consider these things when planning your time for research. 

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

• By Research Guide 

4. Conduct your searches and find the literature. 

• Review the abstracts carefully - this will save you time!
• Many databases will have a search history tab for you to return to for later.
• Use bibliographies and references of research studies to locate others.
• Use citation management software such as Zotero to keep track of your research citations. 

5. Review the literature. 

Some questions to help you analyze the research: 

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

Source: "Literature Review", University of West Florida,  https://libguides.uwf.edu/c.php?g=215113&p=5139469

A literature review is not a summary of the sources but a synthesis of the sources. It is made up of the topics the sources are discussing. Each section of the review is focused on a topic, and the relevant sources are discussed within the context of that topic. 

1. Select the most relevant material from the sources

• Could be material that answers the question directly
• Extract as a direct quote or paraphrase 

2. Arrange that material so you can focus on it apart from the source text itself

• You are now working with fewer words/passages
• Material is all in one place

3. Group similar points, themes, or topics together and label them 

• The labels describe the points, themes, or topics that are the backbone of your paper’s structure

4. Order those points, themes, or topics as you will discuss them in the paper, and turn the labels into actual assertions

• A sentence that makes a point that is directly related to your research question or thesis 

This is now the outline for your literature review. 

Source: "Organizing a Review of the Literature – The Basics", George Mason University Writing Center,  https://writingcenter.gmu.edu/writing-resources/research-based-writing/organizing-literature-reviews-the-basics

• Literature Review Matrix Here is a template on how people tend to organize their thoughts. The matrix template is a good way to write out the key parts of each article and take notes. Downloads as an XLSX file.

The most common way that literature reviews are organized is by theme or author. Find a general pattern of structure for the review. When organizing the review, consider the following: 

• the methodology 
• the quality of the findings or conclusions
• major strengths and weaknesses
• any other important information

Writing Tips: 

• Be selective - Select only the most important points in each source to highlight in the review. It should directly relate to the review's focus.
• Use quotes sparingly.
• Keep your own voice - Your voice (the writer's) should remain front and center. .   
• Aim for one key figure/table per section to illustrate complex content, summarize a large body of relevant data, or describe the order of a process
• Legend below image/figure and above table and always refer to them in text 

Source: "Composing your Literature Review", Florida A&M University,  https://library.famu.edu/c.php?g=577356&p=3982811

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Workshop: Literature Reviews- What you need to know

• How to write a literature review

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The Seven Steps to Producing a Literature Review:

1. Identify your question

2. Review discipline style

3. Search the literature

4. Manage your references

5. Critically analyze and evaluate

6. Synthisize

7. Write the review

• University of North Carolina Writing Center "How To" UNC Chapel Hill Writing Center "How To" on writing a literature review.
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Literature Review - what is a Literature Review, why it is important and how it is done

• Strategies to Find Sources
• Evaluating Literature Reviews and Sources
• Tips for Writing Literature Reviews

Literature Reviews: Useful Sites

Writing tutorials & other resources.

• Citation Resources
• Other Academic Writings
• Useful Resources

The majority of these sites focus on literature reviews in the social sciences unless otherwise noted. For systematic literature reviews, we recommend you to contact directly your subject librarian for help.

• How to Write a Literature Review Nice and concise handout on how to write a literature review
• Six Steps to Writing a Literature Review This blog, written by Tanya Golash-Boza, an Associate Professor of Sociology at the University of California at Merced, a successful PhD, offers a very nice and simple advice on how to write a literature review from the point of view of an experience professional. Tanya's current research is on racial identities and immigration policies. She is currently writing a book on deportees.
• Literature Review and Synthesis (University Writing Center, Indiana University) Excellent handout to teach you how to synthesize (make connections between) multiple sources in your literature review
• How to Write a Historiography (Literature Review for History) This is an excellent site to learn how to write this particular literature review in History.

Literature Reviews: An Overview for Graduate Students. (NCSU Libraries) What is a literature review? What purpose does it serve in research? What should you expect when writing one? 

A selection of sites that offer tutorials and handouts to learn how to write literature reviews and how to use specific writing skills such as paraphrasing and synthesis.

• Literature Review Online Tutorial (North Carolina State University Libraries)
• Literature Review Tutorial (CQ University-Australia)
• Paraphrase: Write it in Your Own Words (OWL Purdue Writing Lab)
• Acknowledging, Paraphrasing and Quoting Sources (UW-Madison's Writing Center) This is an open PDF document with the whole guide on Acknowledging, Paraphrasing and Quoting Sources.
• Synthesize - The Literature Review: A Research Journey Nice explanation by Harvard's Graduate School of Education on what is synthesis. Also, check out the rest of the guide for definitions and videos of faculty and students about the literature review process.
• Introduction to Syntheses Excellent presentation of what is syntheses, different types of it, etc...
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• Last Updated: Jul 3, 2024 10:56 AM
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17 strong academic phrases to write your literature review (+ real examples)

A well-written academic literature review not only builds upon existing knowledge and publications but also involves critical reflection, comparison, contrast, and identifying research gaps. The following 17 strong academic key phrases can assist you in writing a critical and reflective literature review.

Academic key phrases to present existing knowledge in a literature review

The topic has received significant interest within the wider literature..

Example: “ The topic of big data and its integration with AI has received significant interest within the wider literature .” ( Dwivedi et al. 2021, p. 4 )

The topic gained considerable attention in the academic literature in…

Studies have identified….

Example: “ Studies have identified the complexities of implementing AI based systems within government and the public sector .” ( Dwivedi et al. 2021, p. 6 )

Researchers have discussed…

Recent work demonstrated that….

Example: “Recent work demonstrated that dune grasses with similar morphological traits can build contrasting landscapes due to differences in their spatial shoot organization.” ( Van de Ven, 2022 et al., p. 1339 )

Existing research frequently attributes…

Prior research has hypothesized that…, prior studies have found that….

Example:  “ Prior studies have found that court-referred individuals are more likely to complete relationship violence intervention programs (RVIP) than self-referred individuals. ” ( Evans et al. 2022, p. 1 )

Academic key phrases to contrast and compare findings in a literature review

While some scholars…, others…, the findings of scholar a showcase that… . scholar b , on the other hand, found….

Example: “ The findings of Arinto (2016) call for administrators concerning the design of faculty development programs, provision of faculty support, and strategic planning for online distance learning implementation across the institution. Francisco and Nuqui (2020) on the other hand found that the new normal leadership is an adaptive one while staying strong on their commitment. ” ( Asio and Bayucca, 2021, p. 20 )

Interestingly, all the arguments refer to…

This argument is similar to….

If you are looking to elevate your writing and editing skills, I highly recommend enrolling in the course “ Good with Words: Writing and Editing Specialization “, which is a 4 course series offered by the University of Michigan. This comprehensive program is conveniently available as an online course on Coursera, allowing you to learn at your own pace. Plus, upon successful completion, you’ll have the opportunity to earn a valuable certificate to showcase your newfound expertise!

Academic key phrases to highlight research gaps in a literature review

Yet, it remains unknown how…, there is, however, still little research on…, existing studies have failed to address….

Example: “ University–industry relations (UIR) are usually analysed by the knowledge transfer channels, but existing studies have failed to address what knowledge content is being transferred – impacting the technology output aimed by the partnership.”  (Dalmarco et al. 2019, p. 1314 )

Several scholars have recommended to move away…

New approaches are needed to address…, master academia, get new content delivered directly to your inbox, 26 powerful academic phrases to write your introduction (+ real examples), 13 awesome academic phrases to write your methodology (+ real examples), related articles, 10 tips on how to use reference management software smartly and efficiently, separating your self-worth from your phd work, how to introduce yourself in a conference presentation (in six simple steps), how to write effective cover letters for a paper submission.

10 Best Literature Review Tools for Researchers

Boost your research game with these Best Literature Review Tools for Researchers! Uncover hidden gems, organize your findings, and ace your next research paper!

Researchers struggle to identify key sources, extract relevant information, and maintain accuracy while manually conducting literature reviews. This leads to inefficiency, errors, and difficulty in identifying gaps or trends in existing literature.

Table of Contents

Top 10 Literature Review Tools for Researchers: In A Nutshell (2023)

#1. Semantic Scholar – A free, AI-powered research tool for scientific literature

Not all scholarly content may be indexed, and occasional false positives or inaccurate associations can occur. Furthermore, the tool primarily focuses on computer science and related fields, potentially limiting coverage in other disciplines. 

#2. Elicit – Research assistant using language models like GPT-3

Elicit is a game-changing literature review tool that has gained popularity among researchers worldwide. With its user-friendly interface and extensive database of scholarly articles, it streamlines the research process, saving time and effort. 

However, users should be cautious when using Elicit. It is important to verify the credibility and accuracy of the sources found through the tool, as the database encompasses a wide range of publications. 

#3. Scite.Ai – Your personal research assistant

However, while Scite.Ai offers numerous advantages, there are a few aspects to be cautious about. As with any data-driven tool, occasional errors or inaccuracies may arise, necessitating researchers to cross-reference and verify results with other reputable sources. 

Rayyan offers the following paid plans:

#4. DistillerSR – Literature Review Software

Despite occasional technical glitches reported by some users, the developers actively address these issues through updates and improvements, ensuring a better user experience. 

#5. Rayyan – AI Powered Tool for Systematic Literature Reviews

However, it’s important to be aware of a few aspects. The free version of Rayyan has limitations, and upgrading to a premium subscription may be necessary for additional functionalities. 

#6. Consensus – Use AI to find you answers in scientific research

With Consensus, researchers can save significant time by efficiently organizing and accessing relevant research material.People consider Consensus for several reasons. 

Consensus offers both free and paid plans:

#7. RAx – AI-powered reading assistant

#8. lateral – advance your research with ai.

Additionally, researchers must be mindful of potential biases introduced by the tool’s algorithms and should critically evaluate and interpret the results. 

#9. Iris AI – Introducing the researcher workspace

Researchers are drawn to this tool because it saves valuable time by automating the tedious task of literature review and provides comprehensive coverage across multiple disciplines. 

#10. Scholarcy – Summarize your literature through AI

Scholarcy’s automated summarization may not capture the nuanced interpretations or contextual information presented in the full text. 

Final Thoughts

In conclusion, conducting a comprehensive literature review is a crucial aspect of any research project, and the availability of reliable and efficient tools can greatly facilitate this process for researchers. This article has explored the top 10 literature review tools that have gained popularity among researchers.

Q1. What are literature review tools for researchers?

Q2. what criteria should researchers consider when choosing literature review tools.

When choosing literature review tools, researchers should consider factors such as the tool’s search capabilities, database coverage, user interface, collaboration features, citation management, annotation and highlighting options, integration with reference management software, and data extraction capabilities. 

Q3. Are there any literature review tools specifically designed for systematic reviews or meta-analyses?

Meta-analysis support: Some literature review tools include statistical analysis features that assist in conducting meta-analyses. These features can help calculate effect sizes, perform statistical tests, and generate forest plots or other visual representations of the meta-analytic results.

Q4. Can literature review tools help with organizing and annotating collected references?

Integration with citation managers: Some literature review tools integrate with popular citation managers like Zotero, Mendeley, or EndNote, allowing seamless transfer of references and annotations between platforms.

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• Volume 24, Issue 2
• Five tips for developing useful literature summary tables for writing review articles
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• http://orcid.org/0000-0003-0157-5319 Ahtisham Younas 1 , 2 ,
• http://orcid.org/0000-0002-7839-8130 Parveen Ali 3 , 4
• 1 Memorial University of Newfoundland , St John's , Newfoundland , Canada
• 2 Swat College of Nursing , Pakistan
• 3 School of Nursing and Midwifery , University of Sheffield , Sheffield , South Yorkshire , UK
• 4 Sheffield University Interpersonal Violence Research Group , Sheffield University , Sheffield , UK
• Correspondence to Ahtisham Younas, Memorial University of Newfoundland, St John's, NL A1C 5C4, Canada; ay6133{at}mun.ca

https://doi.org/10.1136/ebnurs-2021-103417

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Introduction

Literature reviews offer a critical synthesis of empirical and theoretical literature to assess the strength of evidence, develop guidelines for practice and policymaking, and identify areas for future research. 1 It is often essential and usually the first task in any research endeavour, particularly in masters or doctoral level education. For effective data extraction and rigorous synthesis in reviews, the use of literature summary tables is of utmost importance. A literature summary table provides a synopsis of an included article. It succinctly presents its purpose, methods, findings and other relevant information pertinent to the review. The aim of developing these literature summary tables is to provide the reader with the information at one glance. Since there are multiple types of reviews (eg, systematic, integrative, scoping, critical and mixed methods) with distinct purposes and techniques, 2 there could be various approaches for developing literature summary tables making it a complex task specialty for the novice researchers or reviewers. Here, we offer five tips for authors of the review articles, relevant to all types of reviews, for creating useful and relevant literature summary tables. We also provide examples from our published reviews to illustrate how useful literature summary tables can be developed and what sort of information should be provided.

Tip 1: provide detailed information about frameworks and methods

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Tabular literature summaries from a scoping review. Source: Rasheed et al . 3

The provision of information about conceptual and theoretical frameworks and methods is useful for several reasons. First, in quantitative (reviews synthesising the results of quantitative studies) and mixed reviews (reviews synthesising the results of both qualitative and quantitative studies to address a mixed review question), it allows the readers to assess the congruence of the core findings and methods with the adapted framework and tested assumptions. In qualitative reviews (reviews synthesising results of qualitative studies), this information is beneficial for readers to recognise the underlying philosophical and paradigmatic stance of the authors of the included articles. For example, imagine the authors of an article, included in a review, used phenomenological inquiry for their research. In that case, the review authors and the readers of the review need to know what kind of (transcendental or hermeneutic) philosophical stance guided the inquiry. Review authors should, therefore, include the philosophical stance in their literature summary for the particular article. Second, information about frameworks and methods enables review authors and readers to judge the quality of the research, which allows for discerning the strengths and limitations of the article. For example, if authors of an included article intended to develop a new scale and test its psychometric properties. To achieve this aim, they used a convenience sample of 150 participants and performed exploratory (EFA) and confirmatory factor analysis (CFA) on the same sample. Such an approach would indicate a flawed methodology because EFA and CFA should not be conducted on the same sample. The review authors must include this information in their summary table. Omitting this information from a summary could lead to the inclusion of a flawed article in the review, thereby jeopardising the review’s rigour.

Tip 2: include strengths and limitations for each article

Critical appraisal of individual articles included in a review is crucial for increasing the rigour of the review. Despite using various templates for critical appraisal, authors often do not provide detailed information about each reviewed article’s strengths and limitations. Merely noting the quality score based on standardised critical appraisal templates is not adequate because the readers should be able to identify the reasons for assigning a weak or moderate rating. Many recent critical appraisal checklists (eg, Mixed Methods Appraisal Tool) discourage review authors from assigning a quality score and recommend noting the main strengths and limitations of included studies. It is also vital that methodological and conceptual limitations and strengths of the articles included in the review are provided because not all review articles include empirical research papers. Rather some review synthesises the theoretical aspects of articles. Providing information about conceptual limitations is also important for readers to judge the quality of foundations of the research. For example, if you included a mixed-methods study in the review, reporting the methodological and conceptual limitations about ‘integration’ is critical for evaluating the study’s strength. Suppose the authors only collected qualitative and quantitative data and did not state the intent and timing of integration. In that case, the strength of the study is weak. Integration only occurred at the levels of data collection. However, integration may not have occurred at the analysis, interpretation and reporting levels.

Tip 3: write conceptual contribution of each reviewed article

While reading and evaluating review papers, we have observed that many review authors only provide core results of the article included in a review and do not explain the conceptual contribution offered by the included article. We refer to conceptual contribution as a description of how the article’s key results contribute towards the development of potential codes, themes or subthemes, or emerging patterns that are reported as the review findings. For example, the authors of a review article noted that one of the research articles included in their review demonstrated the usefulness of case studies and reflective logs as strategies for fostering compassion in nursing students. The conceptual contribution of this research article could be that experiential learning is one way to teach compassion to nursing students, as supported by case studies and reflective logs. This conceptual contribution of the article should be mentioned in the literature summary table. Delineating each reviewed article’s conceptual contribution is particularly beneficial in qualitative reviews, mixed-methods reviews, and critical reviews that often focus on developing models and describing or explaining various phenomena. Figure 2 offers an example of a literature summary table. 4

Tabular literature summaries from a critical review. Source: Younas and Maddigan. 4

Tip 4: compose potential themes from each article during summary writing

While developing literature summary tables, many authors use themes or subthemes reported in the given articles as the key results of their own review. Such an approach prevents the review authors from understanding the article’s conceptual contribution, developing rigorous synthesis and drawing reasonable interpretations of results from an individual article. Ultimately, it affects the generation of novel review findings. For example, one of the articles about women’s healthcare-seeking behaviours in developing countries reported a theme ‘social-cultural determinants of health as precursors of delays’. Instead of using this theme as one of the review findings, the reviewers should read and interpret beyond the given description in an article, compare and contrast themes, findings from one article with findings and themes from another article to find similarities and differences and to understand and explain bigger picture for their readers. Therefore, while developing literature summary tables, think twice before using the predeveloped themes. Including your themes in the summary tables (see figure 1 ) demonstrates to the readers that a robust method of data extraction and synthesis has been followed.

Tip 5: create your personalised template for literature summaries

Often templates are available for data extraction and development of literature summary tables. The available templates may be in the form of a table, chart or a structured framework that extracts some essential information about every article. The commonly used information may include authors, purpose, methods, key results and quality scores. While extracting all relevant information is important, such templates should be tailored to meet the needs of the individuals’ review. For example, for a review about the effectiveness of healthcare interventions, a literature summary table must include information about the intervention, its type, content timing, duration, setting, effectiveness, negative consequences, and receivers and implementers’ experiences of its usage. Similarly, literature summary tables for articles included in a meta-synthesis must include information about the participants’ characteristics, research context and conceptual contribution of each reviewed article so as to help the reader make an informed decision about the usefulness or lack of usefulness of the individual article in the review and the whole review.

In conclusion, narrative or systematic reviews are almost always conducted as a part of any educational project (thesis or dissertation) or academic or clinical research. Literature reviews are the foundation of research on a given topic. Robust and high-quality reviews play an instrumental role in guiding research, practice and policymaking. However, the quality of reviews is also contingent on rigorous data extraction and synthesis, which require developing literature summaries. We have outlined five tips that could enhance the quality of the data extraction and synthesis process by developing useful literature summaries.

• Aromataris E ,
• Rasheed SP ,

Twitter @Ahtisham04, @parveenazamali

Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests None declared.

Patient consent for publication Not required.

Provenance and peer review Not commissioned; externally peer reviewed.

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• Literature Review Guidelines

Making sense of what has been written on your topic.

Goals of a literature review:.

Before doing work in primary sources, historians must know what has been written on their topic.  They must be familiar with theories and arguments–as well as facts–that appear in secondary sources.

Before you proceed with your research project, you too must be familiar with the literature: you do not want to waste time on theories that others have disproved and you want to take full advantage of what others have argued.  You want to be able to discuss and analyze your topic.

Your literature review will demonstrate your familiarity with your topic’s secondary literature.

GUIDELINES FOR A LITERATURE REVIEW:

1) LENGTH:  8-10 pages of text for Senior Theses (485) (consult with your professor for other classes), with either footnotes or endnotes and with a works-consulted bibliography. [See also the  citation guide  on this site.]

2) NUMBER OF WORKS REVIEWED: Depends on the assignment, but for Senior Theses (485), at least ten is typical.

3) CHOOSING WORKS:

Your literature review must include enough works to provide evidence of both the breadth and the depth of the research on your topic or, at least, one important angle of it.  The number of works necessary to do this will depend on your topic. For most topics, AT LEAST TEN works (mostly books but also significant scholarly articles) are necessary, although you will not necessarily give all of them equal treatment in your paper (e.g., some might appear in notes rather than the essay). 4) ORGANIZING/ARRANGING THE LITERATURE:

As you uncover the literature (i.e., secondary writing) on your topic, you should determine how the various pieces relate to each other.  Your ability to do so will demonstrate your understanding of the evolution of literature.

You might determine that the literature makes sense when divided by time period, by methodology, by sources, by discipline, by thematic focus, by race, ethnicity, and/or gender of author, or by political ideology.  This list is not exhaustive.  You might also decide to subdivide categories based on other criteria.  There is no “rule” on divisions—historians wrote the literature without consulting each other and without regard to the goal of fitting into a neat, obvious organization useful to students.

The key step is to FIGURE OUT the most logical, clarifying angle.  Do not arbitrarily choose a categorization; use the one that the literature seems to fall into.  How do you do that?  For every source, you should note its thesis, date, author background, methodology, and sources.  Does a pattern appear when you consider such information from each of your sources?  If so, you have a possible thesis about the literature.  If not, you might still have a thesis.

Consider: Are there missing elements in the literature?  For example, no works published during a particular (usually fairly lengthy) time period?  Or do studies appear after long neglect of a topic?  Do interpretations change at some point?  Does the major methodology being used change?  Do interpretations vary based on sources used?

Follow these links for more help on analyzing  historiography  and  historical perspective .

5) CONTENTS OF LITERATURE REVIEW:

The literature review is a research paper with three ingredients:

a) A brief discussion of the issue (the person, event, idea). [While this section should be brief, it needs to set up the thesis and literature that follow.] b) Your thesis about the literature c) A clear argument, using the works on topic as evidence, i.e., you discuss the sources in relation to your thesis, not as a separate topic.

These ingredients must be presented in an essay with an introduction, body, and conclusion.

6) ARGUING YOUR THESIS:

The thesis of a literature review should not only describe how the literature has evolved, but also provide a clear evaluation of that literature.  You should assess the literature in terms of the quality of either individual works or categories of works.  For instance, you might argue that a certain approach (e.g. social history, cultural history, or another) is better because it deals with a more complex view of the issue or because they use a wider array of source materials more effectively. You should also ensure that you integrate that evaluation throughout your argument.  Doing so might include negative assessments of some works in order to reinforce your argument regarding the positive qualities of other works and approaches to the topic.

Within each group, you should provide essential information about each work: the author’s thesis, the work’s title and date, the author’s supporting arguments and major evidence.

In most cases, arranging the sources chronologically by publication date within each section makes the most sense because earlier works influenced later ones in one way or another.  Reference to publication date also indicates that you are aware of this significant historiographical element.

As you discuss each work, DO NOT FORGET WHY YOU ARE DISCUSSING IT.  YOU ARE PRESENTING AND SUPPORTING A THESIS ABOUT THE LITERATURE.

When discussing a particular work for the first time, you should refer to it by the author’s full name, the work’s title, and year of publication (either in parentheses after the title or worked into the sentence).

For example, “The field of slavery studies has recently been transformed by Ben Johnson’s The New Slave (2001)” and “Joe Doe argues in his 1997 study, Slavery in America, that . . . .”

Your paper should always note secondary sources’ relationship to each other, particularly in terms of your thesis about the literature (e.g., “Unlike Smith’s work, Mary Brown’s analysis reaches the conclusion that . . . .” and “Because of Anderson’s reliance on the president’s personal papers, his interpretation differs from Barry’s”). The various pieces of the literature are “related” to each other, so you need to indicate to the reader some of that relationship.  (It helps the reader follow your thesis, and it convinces the reader that you know what you are talking about.)

7) DOCUMENTATION:

Each source you discuss in your paper must be documented using footnotes/endnotes and a bibliography.  Providing author and title and date in the paper is not sufficient.  Use correct Turabian/Chicago Manual of Style form.  [See  Bibliography  and  Footnotes/Endnotes  pages.]

In addition, further supporting, but less significant, sources should be included in  content foot or endnotes .  (e.g., “For a similar argument to Ben Johnson’s, see John Terry, The Slave Who Was New (New York: W. W. Norton, 1985), 3-45.”)

8 ) CONCLUSION OF LITERATURE REVIEW:

Your conclusion should not only reiterate your argument (thesis), but also discuss questions that remain unanswered by the literature.  What has the literature accomplished?  What has not been studied?  What debates need to be settled?

Additional writing guidelines

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Why is it important to do a literature review in research?

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 “A substantive, thorough, sophisticated literature review is a precondition for doing substantive, thorough, sophisticated research”. Boote and Baile 2005

Authors of manuscripts treat writing a literature review as a routine work or a mere formality. But a seasoned one knows the purpose and importance of a well-written literature review.  Since it is one of the basic needs for researches at any level, they have to be done vigilantly. Only then the reader will know that the basics of research have not been neglected.

The aim of any literature review is to summarize and synthesize the arguments and ideas of existing knowledge in a particular field without adding any new contributions.   Being built on existing knowledge they help the researcher to even turn the wheels of the topic of research.  It is possible only with profound knowledge of what is wrong in the existing findings in detail to overpower them.  For other researches, the literature review gives the direction to be headed for its success. 

The common perception of literature review and reality:

As per the common belief, literature reviews are only a summary of the sources related to the research. And many authors of scientific manuscripts believe that they are only surveys of what are the researches are done on the chosen topic.  But on the contrary, it uses published information from pertinent and relevant sources like

• Scholarly books
• Scientific papers
• Latest studies in the field
• Established school of thoughts
• Relevant articles from renowned scientific journals

and many more for a field of study or theory or a particular problem to do the following:

• Summarize into a brief account of all information
• Synthesize the information by restructuring and reorganizing
• Critical evaluation of a concept or a school of thought or ideas
• Familiarize the authors to the extent of knowledge in the particular field
• Encapsulate
• Compare & contrast

By doing the above on the relevant information, it provides the reader of the scientific manuscript with the following for a better understanding of it:

• It establishes the authors’  in-depth understanding and knowledge of their field subject
• It gives the background of the research
• Portrays the scientific manuscript plan of examining the research result
• Illuminates on how the knowledge has changed within the field
• Highlights what has already been done in a particular field
• Information of the generally accepted facts, emerging and current state of the topic of research
• Identifies the research gap that is still unexplored or under-researched fields
• Demonstrates how the research fits within a larger field of study
• Provides an overview of the sources explored during the research of a particular topic

Importance of literature review in research:

The importance of literature review in scientific manuscripts can be condensed into an analytical feature to enable the multifold reach of its significance.  It adds value to the legitimacy of the research in many ways:

• Provides the interpretation of existing literature in light of updated developments in the field to help in establishing the consistency in knowledge and relevancy of existing materials
• It helps in calculating the impact of the latest information in the field by mapping their progress of knowledge.
• It brings out the dialects of contradictions between various thoughts within the field to establish facts
• The research gaps scrutinized initially are further explored to establish the latest facts of theories to add value to the field
• Indicates the current research place in the schema of a particular field
• Provides information for relevancy and coherency to check the research
• Apart from elucidating the continuance of knowledge, it also points out areas that require further investigation and thus aid as a starting point of any future research
• Justifies the research and sets up the research question
• Sets up a theoretical framework comprising the concepts and theories of the research upon which its success can be judged
• Helps to adopt a more appropriate methodology for the research by examining the strengths and weaknesses of existing research in the same field
• Increases the significance of the results by comparing it with the existing literature
• Provides a point of reference by writing the findings in the scientific manuscript
• Helps to get the due credit from the audience for having done the fact-finding and fact-checking mission in the scientific manuscripts
• The more the reference of relevant sources of it could increase more of its trustworthiness with the readers
• Helps to prevent plagiarism by tailoring and uniquely tweaking the scientific manuscript not to repeat other’s original idea
• By preventing plagiarism , it saves the scientific manuscript from rejection and thus also saves a lot of time and money
• Helps to evaluate, condense and synthesize gist in the author’s own words to sharpen the research focus
• Helps to compare and contrast to  show the originality and uniqueness of the research than that of the existing other researches
• Rationalizes the need for conducting the particular research in a specified field
• Helps to collect data accurately for allowing any new methodology of research than the existing ones
• Enables the readers of the manuscript to answer the following questions of its readers for its better chances for publication
• What do the researchers know?
• What do they not know?
• Is the scientific manuscript reliable and trustworthy?
• What are the knowledge gaps of the researcher?

22. It helps the readers to identify the following for further reading of the scientific manuscript:

• What has been already established, discredited and accepted in the particular field of research
• Areas of controversy and conflicts among different schools of thought
• Unsolved problems and issues in the connected field of research
• The emerging trends and approaches
• How the research extends, builds upon and leaves behind from the previous research

A profound literature review with many relevant sources of reference will enhance the chances of the scientific manuscript publication in renowned and reputed scientific journals .

References:

http://www.math.montana.edu/jobo/phdprep/phd6.pdf

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Creating Lit Reviews as Arguments

Annette Markham

Jul 1, 2014

I wrote this practical guide for students in 2003. Since various people are still asking about it, I’ll share it here:

• A literature review is a systematic search of scholarly work surrounding and specifically related to the researcher’s interest/project.
• A literature review is also an argument or set of arguments made after reading previous research and theoretical discussions in the area of interest.
• A literature review is, therefore, both the process of searching through scholarly works and the outcome of this search; a written argument by the researcher that justifies his/her research project.
• A literature review helps the researcher determine where to go next by pointing out what has been accomplished in previous studies, or what is missing in previous studies, or what might be a useful or innovative way of cutting into a phenomenon to contribute to the conversation.
• A literature review is NOT a paper that simply overviews, summarizes, or describes previous studies, although all these things must take place as the researcher prepares the literature review.
• The written review should be narrow in focus but your search for literature and your review of literature is not narrow.
• Reviews do not simply describe or summarize, they evaluate.
• The process of creating a review can be inductive or deductive (deductive is recommended if you already have a study in progress):

(A deductive approach implies that you “choose an area of research, read all the relevant studies, and come up with some meaningful way to organize the studies” [University of Washington Psychology Writing Center handout])

(An inductive approach implies that you begin with an argument/point or organizing theme and read related studies]

Value (and therefore quality) of the review relies on:

• Your ability to find a lot of research related to your general area, read through most of this, and incorporate only the most relevant into your literature review.
• Your ability to guide readers through the literature via your perspective and argument
• The level of evaluation versus simple description and/or summary
• Your ability to identify gaps, analyze controversy, posit future research questions, or justify your own study.

General Procedures/Steps:

• Identify general area or specific theme
• Research thoroughly, in various disciplines and sources
• Read for detail, keeping a chart if necessary
• Brainstorm ideas for a way to synthesize the material, creatively move beyond mere summary/synthesis to build your own argument
• Narrow your scope:  Identify and list themes or arguments
• Pose arguments as claims, in the form of declarative sentences
• Organize the themes into a logical pattern
• Write each argument, using major theories and research findings to help you build evidence and arguments
• Write the intro and conclusion last

Questions to ask yourself:

• What specific research question am I seeking to address?
• Am I looking for issues of methodology, theory, policy?
• Do the research articles match my research question?
• Am I looking in the right places?  Enough places?
• Will the reader find my review useful?  Why or why not?
• Have I included or accounted for opposing viewpoints or findings?

Evaluation Questions to ask about each article or author as you read :

• Does this article fit with other research in the area?  how does it differ?
• Does the author account for variation from other researchers and findings?
• Have I identified the major findings of this author?
• What is the theoretical framework, the rhetorical purpose, and the practical perspective f this author?
• Is the author internally consistent?
• Does the author provide enough evidence to support the claims being made?
• Are the sources of evidence appropriate?
• Do the conclusions follow from the evidence or study findings presented?
• Does the methodology match the type of question being asked?

Tips for Excellence

• Do not rely on too few articles
• Use several disciplines and libraries to broaden your findings
• Search widely, using various types of physical and online searches to avoid missing large or vital areas of research
• Keep the topic narrow and strive for depth rather than breadth of coverage….which essentially says, “narrow your research question.”
• Remember that you are building your own argument as a scholar. You are not simply summarizing the field (a good lit review is not a broad sweeping overview of the topic.  It is your argument about a topic using many different authors and articles to support your points)

To aid your reading and comprehension of difficult materials:

• Read easier articles first
• Read previous review articles or even semi-related lit review articles first
• Do not skip difficult, long, or complex articles:  Simply read, re-read, and digest.
• Read carefully, looking for subtle interpretations or explanations of theoretical concepts
• Give yourself adequate time to do all of the above…..the worst case scenario is that your argument is poor and misinforms you and your reader because you didn’t take the time to read carefully.
• Explore unfamiliar ideas and concepts with textbooks, but don’t take textbook knowledge as “truth”—that’s the whole point of your literature review.  (textbooks are like big, too easy to read, very broad literature reviews)

More tips for writing literature reviews (or for writing any good argument)

• Outline (preview) your arguments in the introduction clearly and precisely
• Use headings to separate categories and major arguments
• Revise sentences that indicate subjectivity (we know everything is subjective, but you don’t want to water down argument by using “I feel,” “I think,” or “I believe.”)
• Avoid other tendencies such as overusing pronouns and vague referents.  Be concrete and specific.
• If your claims are not original, that’s fine. Cite the origin(s). Give others credit for their ideas.
• Again, avoid plagiarism; if the idea or statement is not yours, cite your source.
• Paraphrasing is more common than direct quoting in a lit review (not a hard and fast rule).
• Remember that a literature review is not really just a “review.”  It is your argument, which begins with and builds from and moves beyond the stuff you read.

Why write as an argument?

• The argument format of writing encourages you to build claims supported with evidence or reasoning.
• Stating your points as declarative statements (that could be answered true/false on a quiz) can help you discover your own attitudes, believes, and values.
• Demanding good arguments of ourselves will lead to new and better ideas.
• Demanding good arguments of ourselves will expose weaknesses that might lead to better qualifications of, or necessary shifts in our claims.
• Making claims and defending them with reasoning and evidence from the literature forces the level of discussion beyond summary and compels you to take a position.
• Finding the weakness in the evidence or reasoning supporting your own claims may help you identify weaknesses in the literature, which in turn can expose excellent gaps to fill with your own research.

Document created by Annette Markham in 2003. Content supplemented by the following resources.  Please cite me if you’re using or quoting this document.  Please consult these other good guides for more information.

• Univ. of Washington Psychology Writing Center: http://depts.washington.edu/psywc/handouts/litrev.html  (now probably here:  http://www.psych.uw.edu/psych.php#p=339 )
• University of Toronto Health Sciences Writing Centre: http://www.utoronto.ca/hswriting/lit-review.htm (now probably this:  http://www.writing.utoronto.ca/advice/specific-types-of-writing/literature-review )
• University of Wisconsin-Madison Writing Center http://www.wisc.edu/writing/Handbook/ReviewofLiterature.html
• Damer, T.E. (2000). Attacking faulty reasoning. A practical guide to fallacy-free arguments. Belmont, CA: Thomson Wadsworth.

FANTASTIC ARTICLE! Literally, every sentence in this article is informative & useful – I particularly find the “Evaluation Questions to ask about…” most precious…..this is a great resource for research scholars such as myself attempting to create a logical argument of the vast body of literature that we’ve read. THANK YOU!

Thank you so much for the valuable information you have given us. It would be wonderful, if you show us live brief example of argument from real research. Believe me this the difficulty which I am undergoing now because I am preparing my self to study for doctoral degree great many thanks / Sudanese teacher

Wow!!! This is incredible – such a valuable resource. Thank you so much for sharing!

Amazing post! I really appreciate all the information.

thanks for sharing .

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Building a Strong Literature Review: Words and Phrases to Include

• backlinkworks
• Writing Articles & Reviews
• December 27, 2023

A literature review is an essential part of any academic paper or research project. IT provides a comprehensive overview of the existing literature on a specific topic, identifies gaps in the current knowledge, and sets the context for the research to be conducted. Building a strong literature review requires careful selection of words and phrases to ensure that IT is well-structured, informative, and persuasive. In this article, we will discuss the words and phrases that are crucial for building a strong literature review.

Words and Phrases to Include in a Literature Review

1. “According to” – This phrase is commonly used to introduce evidence from scholarly sources. For example, “According to Smith (2016), the impact of climate change on biodiversity is a pressing concern.”

2. “ IT has been argued that” – This phrase is useful for presenting different viewpoints on a topic. For example, “ IT has been argued that technological advancements have both positive and negative effects on societal well-being.”

3. “Previous research has shown” – This phrase is effective for referencing existing studies that are relevant to the research topic. For example, “Previous research has shown a strong correlation between smoking and lung cancer.”

4. “A significant body of literature” – This phrase is used to indicate the volume and depth of existing research on a particular topic. For example, “A significant body of literature exists on the psychological impact of social media use.”

5. “In line with previous studies” – This phrase is used to establish continuity with existing research findings. For example, “In line with previous studies, our results indicate a positive association between exercise and mental health.”

6. “Key findings suggest” – This phrase is useful for summarizing the main conclusions of the literature review. For example, “Key findings suggest that mindfulness meditation can improve attention and cognitive performance.”

7. “ IT is evident that” – This phrase is used to emphasize the clarity or strength of evidence supporting a particular argument. For example, “ IT is evident that socioeconomic status has a profound impact on educational outcomes.”

8. “This is consistent with the findings of” – This phrase is used to demonstrate the alignment of the current research with existing literature. For example, “This is consistent with the findings of prior studies that have highlighted the importance of early childhood education.”

9. “Existing literature has identified” – This phrase is useful for highlighting specific issues or phenomena that have been documented in prior research. For example, “Existing literature has identified a range of factors that influence consumer purchasing behavior.”

10. “This study builds upon previous research by” – This phrase is used to emphasize the novelty or contribution of the current research. For example, “This study builds upon previous research by examining the long-term effects of climate change on coastal ecosystems.”

A strong literature review is essential for providing a solid foundation for any research endeavor. By incorporating the words and phrases discussed in this article, researchers can effectively convey the relevance, scope, and depth of the existing literature on their chosen topic. Careful selection and deployment of these words and phrases can enhance the clarity, coherence, and persuasiveness of the literature review, ultimately contributing to the overall strength and quality of the research project.

What is the purpose of a literature review?

A literature review serves several purposes, including providing an overview of existing research on a specific topic, identifying gaps in the current knowledge, and setting the context for a new research study. IT also helps to demonstrate the researcher’s familiarity with and understanding of the relevant literature in their field.

How do I structure a literature review?

A literature review typically follows a structured format, including an introduction, the body of the review (organized by themes or topics), and a conclusion. IT should present a coherent and logical argument, synthesizing and critically analyzing the existing literature on the chosen topic.

What are some common mistakes to avoid in a literature review?

Common mistakes in a literature review include focusing too much on summarizing individual studies without providing critical analysis, failing to clearly articulate the relevance of the literature to the research topic, and not including a sufficient variety of sources to support the argument being made. IT is also important to avoid presenting personal opinions without backing them up with evidence from the literature.

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Literature Review vs Research Paper: What’s the Difference?

by  Antony W

June 26, 2024

This is a complete student’s guide to understanding literature review vs research paper.

We’ll teach you what they’re, explain why they’re important, state the difference between the two, and link you to our comprehensive guide on how to write them.

Literature Review Writing Help

Writing a literature review for a thesis, a research paper, or as a standalone assignment takes time. Much of your time will go into research, not to mention you have other assignments to complete. 

If you find writing in college or university overwhelming, get in touch with our literature review writers for hire at 25% discounts and enjoy the flexibility and convenience that comes with professional writing help. We’ll help you do everything, from research and outlining to custom writing and proofreading.

What is a Literature Review?

A literature review document is a secondary source of information that provides an overview of existing knowledge, which you can use to identify gaps or flaws in existing research. In literature review writing, students have to find and read existing publications such as journal articles, analyze the information, and then state their findings.

Credit: Pubrica

You’ll write a literature review to demonstrate your understanding on the topic, show gaps in existing research, and develop an effective methodology and a theoretical framework for your research project.

Your instructor may ask you to write a literature review as a standalone assignment. Even if that’s the case, the rules for writing a review paper don’t change.

In other words, you’ll still focus on evaluating the current research and find gaps around the topic.

Types of Literature Reviews

There are three types of review papers and they’re a follows:

 1. Meta-analysis

In meta-analysis review paper, you combine and compare answers from already published studies on a given subject.

2. Narrative Review

A narrative review paper looks into existing information or research already conducted on a given topic.

3. Systematic Review

You need to do three things if asked to write a systematic review paper.

First, read and understand the question asked. Second, look into research already conducted on the topic. Third, search for the answer to the question from the established research you just read.

What’s a Research Paper?

A research paper is an assignment in which you present your own argument, evaluation, or interpretation of an issue based on independent research.

In a research paper project, you’ll draw some conclusions from what experts have already done, find gaps in their studies, and then draw your own conclusions.

While a research paper is like an academic essay, it tends to be longer and more detailed.

Since they require extended research and attention to details, research papers can take a lot of time to write.

If well researched, your research paper can demonstrate your knowledge about a topic, your ability to engage with multiple sources, and your willingness to contribute original thoughts to an ongoing debate.

Types of Research Papers

 There are two types of research papers and they’re as follows:

 1. Analytical Research Papers

 Similar to analytical essay , and usually in the form of a question, an analytical research paper looks at an issue from a neutral point and gives a clear analysis of the issue.

Your goal is to make the reader understand both sides of the issue in question and leave it to them to decide what side of the analysis to accept.

Unlike an argumentative research paper, an analytical research paper doesn’t include counterarguments. And you can only draw your conclusion based on the information stretched out all through the analysis.

2. Argumentative Research Papers

In an argumentative research paper, you state the subject under study, look into both sides of an issue, pick a stance, and then use solid evidence and objective reasons to defend your position.

In   argumentative writing, your goal isn’t to persuade your audience to take an action. 

Rather, it’s to convince them that your position on the research question is more accurate than the opposing point of views.

Regardless of the type of research paper that you write, you’ll have to follow the standard outline for the assignment to be acceptable for review and marking.

Also, all research paper, regardless of the research question under investigation must include a literature review.

Literature Review vs Research Paper

The table below shows the differences between a literature review (review paper) and a research paper. 

Frequently Asked Questions

1. is there a literature review in a research paper.

A research paper assignment must include a literature review immediately after the introduction chapter.

The chapter is significant because your research work would otherwise be incomplete without knowledge of existing literature. 

2. How Many Literature Review Should Be in Research Paper?

Your research paper  should have only one literature review. Make sure you write the review based on the instructions from your teacher.

Before you start, check the required length, number of sources to summarize, and the format to use. Doing so will help you score top grades for the assignment. 

3. What is the Difference Between Research and Literature?

Whereas literature focuses on gathering, reading, and summarizing information on already established studies, original research involves coming up with new concepts, theories, and ideas that might fill existing gaps in the available literature.

4. How Long is a Literature Review?

How long a literature review should be will depend on several factors, including the level of education, the length of the assignment, the target audience, and the purpose of the review.

For example, a 150-page dissertation can have a literature review of 40 pages on average.

Make sure you talk to your instructor to determine the required length of the assignment.

5. How Does a Literature Review Look Like?

Your literature review shouldn’t be a focus on original research or new information. Rather, it should give a clear overview of the already existing work on the selected topic.

The information to review can come from various sources, including scholarly journal articles , government reports, credible websites, and academic-based books. 

About the author 

Antony W is a professional writer and coach at Help for Assessment. He spends countless hours every day researching and writing great content filled with expert advice on how to write engaging essays, research papers, and assignments.

What is a Literature Review? Tips on Conducting a Review of Literature

A literature review or a review of literature is a text of a scholarly paper, which includes the current knowledge including substantive findings, as well as theoretical and methodological contributions to a particular topic. Literature reviews use secondary sources, and do not report new or original experimental work.

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 (sometimes in the form of an annotated bibliography—see the bottom of the next page), 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.Besides enlarging your knowledge about the topic, writing a literature review lets you gain and demonstrate skills in two areas:

Information seeking: the ability to scan the literature efficiently, using manual or computerized methods, to identify a set of useful articles and books Critical appraisal: the ability to apply principles of analysis to identify unbiased and valid studies. 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 )?
• 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 have 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 analysed 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?

Types of Literature Reviews Most often associated with academic-oriented literature, such as a thesis, dissertation or peer-reviewed journal article, a literature review usually precedes the methodology and results section. Literature reviews are also common in a research proposal or prospectus (the document that is approved before a student formally begins a dissertation or thesis). Its main goals are to situate the current study within the body of literature and to provide context for the particular reader. Literature reviews are a staple for research in nearly every academic field.

A systematic review is a literature review focused on a research question, trying to identify, appraise, select and synthesize all high quality research evidence and arguments relevant to that question. A meta analysis is typically a systematic review using statistical methods to effectively combine the data used on all selected studies to produce a more reliable result.

In summary: A literature review is a piece of discursive prose, not a list describing or summarizing one piece of literature after another. It’s usually a bad sign to see every paragraph beginning with the name of a researcher. Instead, 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

If you are writing an annotated bibliography, you may need to summarize each item briefly, but should still follow through themes and concepts and do some critical assessment of material. Use an overall introduction and conclusion to state the scope of your coverage and to formulate the question, problem, or concept your chosen material illuminates. Usually you will have the option of grouping items into sections—this helps you indicate comparisons and relationships. You may be able to write a paragraph or so to introduce the focus of each section.

Sources http://www.writing.utoronto.ca/advice/specific-types-of-writing/literature-review http://en.wikipedia.org/wiki/Literature_review

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Advantages and disadvantages of literature review

This comprehensive article explores some of the advantages and disadvantages of literature review in research. Reviewing relevant literature is a key area in research, and indeed, it is a research activity in itself. It helps researchers investigate a particular topic in detail. However, it has some limitations as well.

What is literature review?

In order to understand the advantages and disadvantages of literature review, it is important to understand what a literature review is and how it differs from other methods of research. According to Jones and Gratton (2009) a literature review essentially consists of critically reading, evaluating, and organising existing literature on a topic to assess the state of knowledge in the area. It is sometimes called critical review.

A literature review is a select analysis of existing research which is relevant to a researcher’s selected topic, showing how it relates to their investigation. It explains and justifies how their investigation may help answer some of the questions or gaps in the chosen area of study (University of Reading, 2022).

A literature review is a term used in the field of research to describe a systematic and methodical investigation of the relevant literature on a particular topic. In other words, it is an analysis of existing research on a topic in order to identify any relevant studies and draw conclusions about the topic.

A literature review is not the same as a bibliography or a database search. Rather than simply listing references to sources of information, a literature review involves critically evaluating and summarizing existing research on a topic. As such, it is a much more detailed and complex process than simply searching databases and websites, and it requires a lot of effort and skills.

Advantages of literature review

Information synthesis

A literature review is a very thorough and methodical exercise. It can be used to synthesize information and draw conclusions about a particular topic. Through a careful evaluation and critical summarization, researchers can draw a clear and comprehensive picture of the chosen topic.

Familiarity with the current knowledge

According to the University of Illinois (2022), literature reviews allow researchers to gain familiarity with the existing knowledge in their selected field, as well as the boundaries and limitations of that field.

Creation of new body of knowledge

One of the key advantages of literature review is that it creates new body of knowledge. Through careful evaluation and critical summarisation, researchers can create a new body of knowledge and enrich the field of study.

Answers to a range of questions

Literature reviews help researchers analyse the existing body of knowledge to determine the answers to a range of questions concerning a particular subject.

Disadvantages of literature review

Time consuming

As a literature review involves collecting and evaluating research and summarizing the findings, it requires a significant amount of time. To conduct a comprehensive review, researchers need to read many different articles and analyse a lot of data. This means that their review will take a long time to complete.

Lack of quality sources  

Researchers are expected to use a wide variety of sources of information to present a comprehensive review. However, it may sometimes be challenging for them to identify the quality sources because of the availability of huge numbers in their chosen field. It may also happen because of the lack of past empirical work, particularly if the selected topic is an unpopular one.

Descriptive writing

One of the major disadvantages of literature review is that instead of critical appreciation, some researchers end up developing reviews that are mostly descriptive. Their reviews are often more like summaries of the work of other writers and lack in criticality. It is worth noting that they must go beyond describing the literature.

Key features of literature review

Clear organisation

A literature review is typically a very critical and thorough process. Universities usually recommend students a particular structure to develop their reviews. Like all other academic writings, a review starts with an introduction and ends with a conclusion. Between the beginning and the end, researchers present the main body of the review containing the critical discussion of sources.

No obvious bias

A key feature of a literature review is that it should be very unbiased and objective. However, it should be mentioned that researchers may sometimes be influenced by their own opinions of the world.

Proper citation

One of the key features of literature review is that it must be properly cited. Researchers should include all the sources that they have used for information. They must do citations and provide a reference list by the end in line with a recognized referencing system such as Harvard.

To conclude this article, it can be said that a literature review is a type of research that seeks to examine and summarise existing research on a particular topic. It is an essential part of a dissertation/thesis. However, it is not an easy thing to handle by an inexperienced person. It also requires a lot of time and patience.

Hope you like this ‘Advantages and disadvantages of literature review’. Please share this with others to support our research work.

Other useful articles:

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Last update: 08 May 2022

References:

Jones, I., & Gratton, C. (2009) Research Methods for Sports Shttps://www.howandwhat.net/new/evaluate-website-content/tudies, 2 nd edition, London: Routledge

University of Illinois (2022) Literature review, available at: https://www.uis.edu/learning-hub/writing-resources/handouts/learning-hub/literature-review (accessed 08 May 2022)

University of Reading (2022) Literature reviews, available at: https://libguides.reading.ac.uk/literaturereview/starting (accessed 07 May 2022)

Author: M Rahman

M Rahman writes extensively online and offline with an emphasis on business management, marketing, and tourism. He is a lecturer in Management and Marketing. He holds an MSc in Tourism & Hospitality from the University of Sunderland. Also, graduated from Leeds Metropolitan University with a BA in Business & Management Studies and completed a DTLLS (Diploma in Teaching in the Life-Long Learning Sector) from London South Bank University.

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• Nutrition users’ guides: systematic reviews part 1 –structured guide for methodological assessment, interpretation and application of systematic reviews and meta-analyses of non-randomised nutritional epidemiology studies
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• Dena Zeraatkar 1 , 2 ,
• Russell J de Souza 1 ,
• Gordon H Guyatt 1 , 3 ,
• Malgorzata M Bala 4 ,
• Pablo Alonso-Coello 5 , 6 , 7 and
• http://orcid.org/0000-0001-8872-8626 Bradley C Johnston 8 , 9 , 10
• 1 Department of Health Research Methods, Evidence & Impact , McMaster University , Hamilton , Ontario , Canada
• 2 Department of Anesthesia , McMaster University , Hamilton , Ontario , Canada
• 3 Department of Medicine , McMaster University , Hamilton , Ontario , Canada
• 4 Chair of Epidemiology and Preventive Medicine, Department of Hygiene and Dietetics , Jagiellonian University Medical College , Krakow , Poland
• 5 Iberomerican Cochrane Centre, Clinical Epidemiology and Public Health Department , Institute of Biomedical Research of Barcelona , Barcelona , Spain
• 6 Institut de Recerca Sant Pau (IR SANT PAU), Sant Quintí , Barcelona , Spain
• 7 Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP) , Madrid , Spain
• 8 Department of Nutrition , College of Agriculture and Life Sciences, Texas A&M University , College Station , Texas , USA
• 9 Department of Epidemiology & Biostatistics , School of Public Health, Texas A&M University , College Station , Texas , USA
• 10 Health Research Methods, Evidence and Impact , McMaster University , Hamilton , Ontario , Canada
• Correspondence to Dr Bradley C Johnston; bradley.johnston{at}tamu.edu ; Dr Dena Zeraatkar; dena.zera{at}gmail.com

Due to the challenges of conducting randomised controlled trials (randomised trials) of dietary interventions, evidence in nutrition often comes from non-randomised (observational) studies of nutritional exposures—called nutritional epidemiology studies. When using systematic reviews of such studies to advise patients or populations on optimal dietary habits, users of the evidence (eg, healthcare professionals such as clinicians, health service and policy workers) should first evaluate the rigour (validity) and utility (applicability) of the systematic review. Issues in making this judgement include whether the review addressed a sensible question; included an exhaustive literature search; was scrupulous in the selection of studies and the collection of data; and presented results in a useful manner. For sufficiently rigorous and useful reviews, evidence users must subsequently evaluate the certainty of the findings, which depends on assessments of risk of bias, inconsistency, imprecision, indirectness, effect size, dose-response and the likelihood of publication bias. Given the challenges of nutritional epidemiology, evidence users need to be diligent in assessing whether studies provide evidence of sufficient certainty to allow confident recommendations for patients regarding nutrition and dietary interventions.

• Dietary patterns
• Nutritional treatment
• Medical education
• Evidence based practice
• Critical appraisal

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Data sharing not applicable as no data sets generated and/or analysed for this study.

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See:  http://creativecommons.org/licenses/by-nc/4.0/ .

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What is a systematic review and meta-analysis?

A systematic review identifies, evaluates and summarises the findings of all relevant primary studies addressing a particular question. It is often, but not always, accompanied by a meta-analysis, which is the statistical pooling of data across studies to produce a single effect estimate.

Systematic reviews and meta-analyses have become foundational to evidence-based clinical practice. For example, standards for producing trustworthy guidelines require all recommendations be based on rigorous and comprehensive systematic reviews of the evidence. 1 Failing to base clinical care ( box 1 ) and guideline recommendations on systematic reviews risks overlooking important evidence, selectively choosing favourable evidence or neglecting important limitations of the evidence.

Clinical scenario

You are a family doctor (general practitioner) following a healthy 45-year-old female patient. She reports having recently come across a series of news articles on the alleged adverse health effects of red and processed meat. She is concerned about her cardiovascular health and her risk for cancer and inquires whether reducing her intake of red and processed meat (currently at four and two servings/week, respectively) is important. She also indicates that her meat consumption is mostly from local sources using sustainable (regenerative), ethical and humane farming practices. You recall having read a series of systematic review articles on this topic of meat and health outcomes. You ask the patient to return in 2weeks for further advice.

You formulate the relevant clinical question: in healthy middle-aged adults, does the reduction of red and processed meat intake reduce the risk of adverse cardiovascular and cancer health outcomes? You refer to the series of articles you recall having read on the topic—a guideline and a series of supporting systematic reviews. The guideline, published by an international consortium of methodologists, nutrition researchers and clinicians, called NutriRECS, provides a weak recommendation for adults to continue their current levels of red and processed meat consumption. 46 The systematic reviews summarise the evidence from randomised trials, 42 cohort studies reporting on cardiovascular outcomes, 43 cohort studies reporting on cancer outcomes 44 and cohort studies reporting on the effects of dietary patterns low or high in red and processed meat on cardiovascular and cancer outcomes. 45

There are two aspects to evaluating a systematic review and meta-analysis (SRMA), both within and outside of nutritional epidemiology ( box 2 ). The first has to do with the methodological rigour (validity) and utility (applicability) of SRMA. These issues are discussed in the first half of this manuscript. The second set of issues addresses the certainty (quality) of evidence summarised in the SRMA. These issues are discussed in the second half of the manuscript. While a poorly conducted SRMA is of little use and may be misleading if the body of evidence has important limitations, a well-conducted SRMA may only provide low or very low certainty evidence, evidence that is still important for transparent and informed clinical decision-making.

Guide for evaluating validity, applying the results and assessing the certainty of evidence of a systematic review and meta-analysis

Evaluate validity and applicability of the systematic review.

Did the review explicitly address a relevant question?

Were methods for identifying and selecting studies and collecting data sufficiently rigorous?

Did the review appropriately synthesise data and report results that are ready for application?

Assess the certainty (quality) of the evidence

How serious is the risk of bias in the body of evidence?

Are the results consistent across studies?

How precise are the results?

Do the results directly apply to my patient?

Is there concern about publication bias?

Are there reasons to be more certain of findings based on effect size, credible dose-response gradient and/or direction of plausible confounders?

This article describes considerations in evaluating and applying SRMAs in nutrition and draws from the JAMA Users’ Guides series. 2 Given that SRMAs of non-randomised studies (eg, cohort, case–control studies) addressing nutritional exposures—often referred to as nutritional epidemiology studies—require very unique considerations, 3 the primary focus of the first of two articles on nutrition systematic reviews will focus on synthesising non-randomised studies. Part 2 will focus on systematic reviews of randomised clinical trials.

Evaluate the validity and applicability of the systematic review

In using the results of an SRMA to guide clinical or public health decisions, evidence users will need to judge the validity and applicability of the SRMA. The validity of an SRMA may be undermined by limitations such as an incomprehensive search for eligible studies or inappropriate eligibility criteria 2 and its applicability by issues such as addressing an irrelevant question or failing to synthesise data and report results that are ready for application. 2

1. Did the review address a relevant question?

The first step in addressing the applicability of an SRMA of nutritional epidemiology studies is assessing whether authors have stated explicit eligibility criteria that specify the population, exposure, comparator and outcome(s) of interest (frequently referred to as PECO—a variation of PICO used for therapeutic interventional studies). In nutritional epidemiology, the exposure may be a food, food compound (eg, micronutrient, macronutrient, bioactive compound) or dietary pattern. Unlike SRMAs of therapeutic interventions, where an intervention is compared with an alternative intervention (or standard care), SRMAs of nutritional exposures typically compare individuals with a higher intake of exposure (or higher adherence to a dietary pattern) to those with lower intake (or lower adherence to a dietary pattern).

For an SRMA to be optimally useful, it should account for the foods or food compounds that are consumed instead of the exposure of interest, which may also impact the risk for the outcome under study. Investigators may address this issue by summarising results from substitution models or joint analyses, analytical approaches to estimating the effects of the substitution of one food or food compound for another or the joint effects of two or more exposures ( box 3 ). 4 Despite addressing a more specific causal question, substitution models also come with limitations. They are statistical exercises and do not actually account for how people in the real world adapt their diet to accommodate a dietary modification. Foods and diets are also complex mixtures and substitution models may oversimplify their interactions. These models are also subject to the same limitations as other nutrition models, which are described later in this manuscript.

Substitution models

A review addressing sugar-sweetened beverages, for example, summarised results from substitution models to estimate the effects of replacing sugar-sweetened beverages with other beverage alternatives (eg, water, milk, juice, coffee). 52 The review found the substitution of sugar-sweetened beverages with other beverage alternatives may have a positive effect on body weight and composition, but this positive effect is likely larger for the replacement of sugar-sweetened beverages with water.

SRMAs of observational studies addressing the impact of alternative diets are almost always concerned with the effect of those diets—that is, they address their causal impact on patient-important outcomes. Given that causation is the issue at hand, authors should use causal language—though they should, they may not and this is potentially confusing. 5 While many SRMAs of diet exposures or interventions do not conduct or report on the certainty of evidence, 6 it will be up to evidence users to discern the extent to which SRMA results indeed support causal inference (ie, based on Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidance provide moderate, low or very low certainty evidence—they will very seldom provide high certainty evidence) on an outcome by outcome basis.

In this manuscript, to align with their causal intent we use causal language to refer to estimates from SRMAs of observational studies. However, we qualify causal statements with recommended GRADE language to express uncertainty (eg, ‘likely’ or ‘probably’ for moderate certainty evidence; ‘possibly’ or ‘may’ for low certainty; and ‘very uncertain’ for very low certainty evidence). 7

2. Were methods for identifying and selecting studies and collecting data sufficiently rigorous?

SRMAs are at risk of presenting misleading results if they fail to include all eligible studies. For most questions, SRMAs that search MEDLINE and EMBASE, or databases with similar coverage, likely include all or nearly all relevant published studies. For some questions, however, MEDLINE and EMBASE may not be sufficient and it is difficult to know in advance whether a more extensive search is necessary. 8 9 Hence, reviews should always conduct an exhaustive search of the literature that includes the following: study registries, bibliographies of included studies, doctoral theses (eg, EBSCO Open Dissertations, ProQuest, BIOSIS), abstracts from relevant scientific meetings and soliciting experts for relevant published and unpublished studies. 8 10 Further, SRMAs should reduce the opportunity for biases and errors in the selection of studies and the collection of data by ensuring that these processes are conducted independently and in duplicate.

3. Did the review appropriately synthesise and report results that are ready for application?

When using an SRMA to inform inferences about the effect of the intake of a food or food compound on the risk for a health outcome, evidence users should look for results from a dose-response meta-analysis that summarises the relationship between the quantity of the exposure and the risk for the outcome. 11 12 Evidence users should also pay close attention to the quantity of the exposure corresponding to which results are presented and judge whether the quantity is reasonable ( box 4 ). A review may, for example, present the risk difference for adverse cardiovascular outcomes associated with 5 servings/day or 20 servings/day of fruits and vegetables; the latter may be a larger and more impressive effect but may not be reasonable because few studies, if any, reported on the effects of 20 servings/day and the review likely extrapolated the effect from lower quantities of intake. Further, consuming 20 servings/day of fruits and vegetables is not practical for most people.

Dose-response meta-analyses from NutriRECS reviews of cohort studies

Below, figure 1 presents the relative risk of type 2 diabetes corresponding to various servings of processed meat intake per week compared with zero servings/week, derived from a non-linear model. Since these results are derived from a non-linear model, the magnitude of change in the risk of type 2 diabetes will depend on the baseline intake of processed meat.

The dose-response effect of nutritional exposure on a health outcome may be linear or non-linear, both of which may be modelled using dose-response meta-analysis. Evidence users can convert effect estimates from linear dose-response meta-analysis to correspond to different quantities of the exposure by simple algebraic formulae. For non-linear dose-response meta-analysis, SRMAs typically present a graph that depicts the relationship between the exposure and outcome, which evidence users can use to approximate effects corresponding to different quantities of the exposure.

SRMAs may also present results from meta-analyses comparing extreme categories of exposure (eg, a meta-analysis comparing the incidence of an outcome in the highest quantile of intake of a food or food compound to the incidence in the lowest quantile). Despite challenges with their interpretation, such analyses remain common. 6 13 For exposures for which there is no comparable measure of consumption or adherence across studies, such as a posteriori derived dietary patterns (ie, dietary patterns that are derived by methods like factor analysis and principal component analysis), meta-analyses comparing extreme quantiles may be the only feasible approach to pool data. Because such analyses are difficult to interpret, evidence users should be cautious when SRMAs present only comparisons of extreme categories of exposure. 14 15

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Non-linear effect of processed meat on type 2 diabetes. The solid black line represents the point estimate, the shaded region represents the 95% CIs and the tick marks represent the positions of the study-specific estimates.

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Relative effect estimates for cardiovascular mortality corresponding to different quantities of intake of unprocessed red and processed meat from a dose-response meta-analysis

When reporting SRMA results, ideally, authors should present absolute effects—the effect of an exposure expressed as the rate of the outcome (eg, risk differences, number needed to treat or harm) rather than the relative effects (ie, relative risk, OR, HR) alone. SRMAs most often meta-analyse relative effects because they tend to be similar across populations (while also providing more compelling [exaggerated] results). 16 Absolute effects, however, are essential for realistic and intuitive decision-making and without them evidence users cannot help their patients make rational decisions. 17 18 When absolute effects are presented, evidence users should judge whether the population risk estimates used for their calculation are sufficiently similar to the baseline risk of the outcome in their patient. 13 Unfortunately, SRMAs of nutritional epidemiology studies seldom present absolute effects. 6 When absolute effects are not presented, evidence users can calculate them using population risk estimates ( box 5 ). 13 19

Absolute effects from NutriRECS reviews of cohort studies

The NutriRECS systematic review and meta-analyses of cohort studies present absolute effect estimates corresponding to a reduction of red and processed meat of three servings/week, 43 44 a reduction the authors thought might be feasible for most people. Population risks for cardiometabolic outcomes were sourced from the Emerging Risk Factors Collaboration, a consortium of over 100 cohorts, primarily from North America and Western Europe, that includes mostly middle-aged to older adults who were omnivores, while for cancer outcomes NutriRECS used GLOBOCAN, a repository of risk estimates from national cancer registries. Table 2 presents the absolute effects of cardiovascular mortality, type 2 diabetes and cancer mortality. 46

Relative and absolute effect estimates for cardiovascular mortality, type 2 diabetes and cancer mortality

To calculate absolute effects, evidence users can multiply the relative risk (including the lower and upper CIs) by the population risk. For reviews that present results as ORs or HRs, users can calculate absolute effects using alternative formulae: 19 20

Rate the certainty (quality) of the evidence

While results from a body of evidence may appear highly effective, our certainty in the body of evidence may be undermined by issues such as limitations in study designs or differences between the questions addressed in studies and the clinical or public health question of interest. Hence, optimal decision-making also requires consideration of the certainty (quality) of evidence. Several approaches to evaluate the certainty of evidence are available. 21 One such system is the GRADE approach. 22 The GRADE approach is by far the most commonly used system to evaluate the certainty of evidence—is it used by over 100 organisations worldwide, including the WHO, the Cochrane Collaboration and the American Academy of Nutrition and Dietetics and has evolved into a benchmark for the validity of reviews and guidelines. The GRADE approach intends to improve the interpretation of evidence for healthcare decision-making based on a common and transparent standard. 22

Original GRADE guidance proposed that for questions of causal inference, a body of evidence comprised of randomised trials starts at high certainty and non-randomised studies start at low certainty. 23 This is because, randomised trials, by virtue of randomisation, may achieve balance (more or less) in both known and unknown prognostic factors such that any observed differences in outcomes between randomised arms can be more confidently attributed to the intervention under investigation. 24 In non-randomised studies, however, participants with and without exposure may differ with regard to prognostic factors such that any differences in outcomes between participants may be an artefact of differences in other prognostic factors. 24 Even if investigators use sophisticated design and analytical methods to adjust for a comprehensive list of prognostic factors, important factors that are unknown or unmeasured may still influence results. This phenomenon is called residual confounding and is the reason why non-randomised studies are initially rated at low certainty.

Newer GRADE guidance now suggests that a body of evidence comprised of non-randomised studies can also start at high certainty and the certainty of evidence may be downgraded by considering limitations of the evidence in comparison to a ‘target trial’—a hypothetical trial, without any limitations, that may or may not be feasible, addressing the question of interest. 25 Using this approach, however, a body of evidence comprised of non-randomised studies will almost always still land at low or very low certainty due to concerns with residual confounding.

The certainty of a body of evidence may be rated down by one or more levels due to concerns related to five factors: risk of bias (ie, study limitations that may lead to systematic underestimation or overestimation), inconsistency (ie, unexplained heterogeneity in results across studies), indirectness (ie, differences between the questions addressed in studies and the clinical or public health question of interest), imprecision (ie, number of events or participants and the magnitude of CIs around an estimate in relation to the minimum difference in the outcome that patients or the target population finds important) and publication bias (ie, the tendency for studies with statistically significant results or positive results to be published, published faster or published in journals with higher visibility). The certainty of a body of non-randomised studies may also be rated up in select scenarios: when there is a valid dose-response relationship, a large effect (eg, relative risk <0.5or >2.0), or when all plausible confounders act in the opposite direction than the observed effect. 26 A description of these issues follows.

GRADE, initially critiqued for its limited applicability to environmental epidemiology, has broadened its scope. For example, it has established the Environmental and Occupational Health Project Group, which has published guidance on the application of GRADE to environmental and occupational hazards, which also apply to nutritional epidemiology. 3 27–30

Below, we describe considerations in assessing the certainty of evidence presented by SRMAs. If an SRMA assesses the certainty of evidence using these considerations, evidence users will need to consider whether they agree with the judgements presented by the authors. Conversely, if an SRMA does not present an assessment of the certainty of evidence, evidence users can make judgements about the certainty considering the aforementioned criteria, while keeping in mind that study results that firmly support a causal inference statement should typically be accompanied by high certainty evidence based on the GRADE approach.

4. How serious is the risk of bias in the body of evidence?

Users of the evidence should be cautious about applying evidence from SRMAs when most of the evidence comes from studies that are at high risk of bias. A well-conducted review will assess the risk of bias of primary studies—though based on one systematic survey, most SRMAs of nutritional epidemiology studies do not use appropriate and comprehensive criteria and so evidence users should be cautious about accepting the authors’ interpretation of the degree of risk of bias without further considerations. 31

Bias in non-randomised studies may arise due to confounding bias, inappropriate criteria for the selection of participants, errors in the measurement of the exposure, missing data, errors in the measurement of the outcome and selective reporting of results. 32 33 To our knowledge, until recently, there was no risk of bias tools that comprehensively accounted for these biases. The ROBINS-E (Risk Of Bias In Non-Randomized Studies - Exposure) tool, a new risk-of-bias tool for non-randomised studies of exposures, improves on previous risk-of-bias tools by addressing these sources of bias ( box 6 ). 32

Risk of bias in NutriRECS reviews of cohort studies

In the NutriRECS systematic reviews with meta-analyses (SRMAs) of cohort studies, the risk of bias is assessed using ad hoc criteria instead of a known risk of bias tools (eg, Ottawa-Newcastle instrument) due to the limitations of such tools at the time of NutriRECS publications. The ad hoc criteria addressed confounding, the selection of participants, measurement of the exposure, errors in the measurement of the outcome and missing outcome data. 43–45 53

Reviews that use ad hoc criteria to assess risk of bias rather than established risk of bias tools may neglect important considerations of risk of bias. The ad hoc risk of bias criteria used in the NutriRECS SRMAs of cohort studies, for example, do not include selective reporting. The discussion section of the SRMA report, however, acknowledges that all studies are at risk of selective reporting bias due to the lack of standard practices for the registration of protocols and statistical analysis plans of nutritional epidemiology studies.

In the application of GRADE, the NutriRECS SRMAs rated down the certainty of evidence when the evidence came primarily from studies at high risk of bias. For example, the dose-response evidence on unprocessed red meat and cardiovascular mortality came from seven cohort studies, four of which were at high risk of bias due to the lack of periodically repeated measurement of diet and inadequate adjustment for confounders. 43 Given these issues, the authors rated the evidence as very low certainty.

In nutritional epidemiology studies, confounding and bias related to measurement of the exposure represent major areas of concern. Confounders are variables that are correlated with the exposure of interest and have a causal effect on the outcome of interest. Confounding occurs when there are differences in confounding variables between exposure groups. If those who consume more red meat, for example, are more likely to be obese and exercise less, results may appear to show an increase in cardiovascular disease with increased consumption of red meat, which may actually be due to these other effect-modifying variables. Investigators deal with confounding by restricting the study sample to ≥1 levels of confounding factors, matching or statistical methods, such as stratified analyses or adjustment through regression models. 34 At minimum, evidence users should ensure that primary studies control for age, sex, smoking and socioeconomic status. When studies included in the review do not control for these variables, confounding is highly probable. Further, it must be noted that adjusting for factors like smoking, which vary extensively by person-year or decade, is a crude adjustment at best.

Depending on the question of interest, adjustment for other confounding variables will also be necessary. The confounders that are adjusted for in studies are typically presented in a table of study characteristics (this is usually the first table of the SRMA). Users of the evidence should carefully review the confounders for which primary studies adjust and ensure that studies adjust for all suspected confounders.

Even when studies control for all suspected confounders, however, the problem that remains is that studies will yield unbiased results only if all confounders are known—which they seldom are—and if known confounders are measured accurately and can easily be adjusted for (eg, biological sex). Because of this inevitable uncertainty, in most cases, SRMAs of nutritional epidemiology studies will yield only low certainty evidence.

A second issue is the measurement of dietary exposures. Users of the evidence should be cautious of reviews that primarily include studies that measure diet using memory recall-based instruments as these measures are subject to serious limitations. 35 Evidence users can typically express more certainty in the results of SRMAs of studies that measure diet using weighted dietary records or established biomarkers (eg, urine sodium excretion, adipose tissue fatty acids). While we are not yet aware of other reliable and valid dietary measures, future advancements and technologies may eventually facilitate improved dietary measurement. 35

5. Are the results consistent across studies?

When results across primary studies in an SRMA are inconsistent, we are less certain of the findings. Evidence users can look for inconsistency by visually inspecting a forest plot for large differences in point estimates or CIs that do not overlap. Users may also gauge inconsistency by looking for statistical indicators of heterogeneity, such as the I 2 statistic (a summary of the magnitude of heterogeneity that ranges from 0% to 100%). A high I 2 statistic (usually I 2 >50%or >60%) suggests that there is substantial heterogeneity ( box 7 ). Statistical methods for detecting heterogeneity, however, have important limitations. For example, the I 2 value is prone to misinterpretation since even small degrees of unimportant inconsistency may translate to high I 2 values if estimates from studies are highly precise. 36

Example of inconsistency

A systematic review and meta-analysis addressing the association between vegetarian diets and metabolic syndrome reports on five cross-sectional studies and calculates a pooled OR of 0.96 (95% CI 0.50 to 1.85). 54 Figure 2 shows the forest plot for the meta-analysis of these studies. The results of each study are represented by squares with horizontal lines depicting 95% CIs. Studies with results to the left of the vertical line suggest that vegetarian diets reduce the risk of metabolic syndrome. Conversely, studies to the right favour an omnivorous diet. Three studies show a moderate to large effect favouring a vegetarian diet whereas two studies show a moderate to large effect favouring an omnivorous diet and there is little overlap in the CIs of these two groups of studies. The I 2 statistic indicates substantial heterogeneity (I 2 =85%). In such a situation, we are less certain of the pooled effect estimate due to the inconsistency of the results of primary studies.

When deciding whether results are consistent, evidence users should not rely completely on statistical indicators of heterogeneity and should instead judge whether differences in the results of studies, if any, would be important to patients or target populations. Evidence users may be concerned that SRMAs include studies too variable in participants to yield useful insights. They need not be too concerned, however. If study participants differ widely and results are nevertheless similar across studies, it tells us that individuals with different characteristics are likely to respond similarly to the intervention, allowing the application of the results to a wide range of patients or populations. 37 Evidence users might also encounter heterogeneity that is not clinically important. For example, if all studies suggest a dietary exposure is protective against an adverse health outcome but studies suggest that the exposure is protective to different degrees, heterogeneity is less important. 37

Forest plot showing the pooled results of five cross-sectional studies on the association between.

vegetarianism and metabolic syndrome. Ideally, reviewers will anticipate inconsistency, generate a priori hypotheses to explain inconsistency and test their hypotheses using subgroup analyses or meta-regression. Even when reviewers do find a possible subgroup effect, it may still be spurious. Evidence users should use established criteria, considering how likely it is that chance explains the difference in subgroups, whether the studies involve within or between study comparisons (ie, if the hypothesis is the effect differs in men and women, whether men and women were included in the same study or studied separately) and whether authors investigated only a small number of a priori specified hypotheses, to differentiate between spurious and trustworthy subgroup findings. 38

6. How precise are the results?

The width of the 95% CI represents the range in which the true effect plausibly lies (for a more detailed explanation of CIs, see a study by O’Brien and Yi 39 ) and is the primary indicator of the precision of SRMA results. We are less certain of the pooled point estimate if the lower and upper boundaries of the CI, were they to represent the true effect, would lead to different dietary advice or actions. 40 We are more certain of the pooled estimate if the lower and upper boundaries of the CI both suggest that there is no important effect, or that there is an important effect. 40 Deciding whether results are sufficiently precise is subjective and evidence users should consider minimal important differences or decision thresholds based on the values and preferences of their patients or target population when making this judgement. 40 41 For example, for the red and processed meat systematic reviews, 42–45 based on the values and preferences of a guideline panel that included members of the public, 46 for fatal outcomes, <10 events per 1000 was considered as ‘little to no benefit’. For non-fatal outcomes (eg, cancer incidence), <20 per 1000 were considered ‘little to no benefit’ over a lifetime ( box 8 ).

Judgements of Imprecision in NutriRECS reviews of cohort studies

The NutriRECS systematic review and meta-analysis (SRMA) of cohort studies addressing cancer reports a relative risk of 0.99 (95% CI 0.89 to 1.09) among people who consume three fewer servings/week of processed meat and overall cancer incidence. 44 Assuming a lifetime population risk of 185 per 1000 people, the reduction of processed meat intake is associated with 2 fewer cases of cancer in 1000, with CIs ranging from 20 fewer to 17 more. The authors of the SRMA considered the results imprecise because they anticipated that people may consider reducing their intake of processed meat if it would prevent 20 cancers in 1000 people followed over a lifetime (the a priori minimal threshold identified by the guideline panel), but would not reduce their intake if it would result in an additional 17 cases of cancer.

7. Do the results directly apply to my patient?

If the populations, exposures or outcomes investigated in primary studies contained in an SRMA differ from the patient or target population of interest, the evidence may not be applicable (called indirectness). For example, SRMAs of nutritional epidemiology studies may investigate the effects of a nutritional exposure on cardiovascular health in individuals who have already developed symptoms of cardiovascular disease (secondary prevention) but may extrapolate these results to individuals without any signs of cardiovascular disease (primary prevention). Similarly, SRMAs may investigate the effects of nutritional exposures on surrogate outcomes (ie, outcomes that are only important to patients or populations due to their correlation, or assumed link, with other outcomes such as blood pressure) as an indirect measure of patient-important outcomes such a stroke or myocardial infarction. 47 Judgements regarding indirectness depend on whether any differences between the characteristics of studies and the clinical or public health question of interest would lead to an appreciable change in the direction or magnitude of the effect ( box 9 ).

Example of indirectness

A systematic review and meta-analysis (SRMA) on the relationship between the early introduction of fish to the infant diet and the risk of allergic disease considered the evidence indirect because studies measured allergic sensitisation, a surrogate for allergic disease. 55 Conversely, an SRMA on the effects of sugar intake on dental caries did not consider the evidence indirect despite most studies having only included children, because the authors considered the aetiology of dental caries to be identical in children and adults. 56

8. Is there concern about publication bias?

Findings from an SRMA will be biased when results from studies that are published and available for inclusion in the SRMA differ from those that are unpublished or unavailable. Sometimes, studies that are published and available show results that are more interesting or provocative than those that are unpublished and unavailable. Bias due to missing studies, called publication bias, is likely frequent in nutritional epidemiology due to the lack of standard registration practices for protocols, which allows investigators to explore a large number of exposures and outcomes and to report only results that yield interesting findings.

One clue that publication bias exists is if results from smaller studies—that are typically more likely to be published and are thus at higher risk for publication bias—are different from larger studies—studies that are at lower risk of publication bias. This is often referred to as ‘small study effects’. To assess for publication bias, evidence users should start by evaluating how comprehensive (ie, systematic) the search was (see above). SRMA authors should then look for publication bias using visual inspection of funnel plots, and look for statistical tests, such as Egger’s test and Begg’s test, that relate the precision of studies to their effect estimates ( box 10 ). 48 49 These methods, however, have important limitations. Statistical tests for publication bias, for example, are almost always underpowered. Further, even when there is statistical evidence that effects from smaller studies are different from larger studies (ie, ‘small study effects’), publication bias is only one plausible explanation (another is that smaller and larger studies differ in other important ways, such as risk of bias).

Example of publication bias

A systematic review and meta-analysis on the relationship between the frequency of family meals and children’s health found frequent family meals to be associated with lower body mass index (BMI) (r=−0.05, 95%CI −0.06 to −0.03). 57 Figure 3 shows a funnel plot that relates the effect sizes reported in studies (on the x-axis) to a measure of the size of the studies (SE on the y-axis). The dark circles represent the studies included in the review. These studies are asymmetrically distributed in the funnel plot: smaller studies (presented towards the lower half of the figure) show frequent family meals to be associated with lower BMI, whereas this effect is not observed in larger studies (at the top of the figure). The authors use a method called ‘trim and fill’ to identify and correct this asymmetry. The ‘imputed studies’ are shown in white circles. Egger’s test is also statistically significant (p=0.001). We may be less certain of the relationship between the frequency of family meals and children’s BMI due to the evidence of potential publication bias.

A funnel plot to help assess publication bias from a systematic review and meta-analysis on the relationship between the frequency of family meals and children’s BMI. White circles represent imputed studies. BMI, body mass index.

9. Are there reasons to be more certain of findings based on effect size, credible dose-response gradient and/or direction of plausible confounders?

Three uncommon situations can sometimes make us more certain of findings of non-randomised studies. First, when the observed effect is large (typically a relative risk (RR)>2.0or RR<0.5), biases, such as confounding, are less likely to fully explain the observed effect. Large effects will very rarely, if ever, occur in nutritional epidemiology studies since the foods and nutrients to which participants are typically exposed typically have small effects on health, though these effects may accumulate over long durations of exposure. 50

Second, we may be more certain of results when we observe a dose-response gradient, particularly if biases about which we are concerned are unlikely to produce spurious dose-response associations. It must be noted, however, that nutritional exposures are highly correlated with one another, 29 51 which makes spurious dose-response associations highly plausible. 29

The third situation—when all plausible confounders would act in the opposite direction than the direction of the observed effect—is also unlikely to occur in nutrition because we seldom are aware of all plausible confounders. Overall, because situations that make us more certain of findings of non-randomised studies seldom occur in nutrition, SRMAs of nutritional epidemiology studies usually provide only low to very low certainty evidence ( box 11 ).

Clinical scenario resolution

We now return to our opening clinical scenario. Although the reviews do not address the effects associated with replacing red or processed meat with particular alternative foods, the reviews did have applicability, addressing a relevant question: the effects of reducing red and processed meat intake on adverse cardiovascular and cancer health outcomes. The systematic review and meta-analyses are methodologically rigorous (valid): they followed a priori specified methods; included an exhaustive search for all relevant studies; performed screening and extraction of data in duplicate; and used appropriate methods for the quantitative synthesis of results across studies, including dose-response meta-analyses.

The authors apply the Grading of Recommendations, Development and Evaluation approach to assess the certainty of evidence. Randomised trials provided low to very low certainty evidence that diets lower in red meat may result in some small reductions in adverse cardiovascular and cancer health outcomes. 42 Cohort studies sometimes provided low certainty evidence (if adequately adjusted, with consistent results) and sometimes very low certainty (certainty rated down for risk of bias concerns of inadequate adjustment for confounding and lack of periodic repeated measurement of diet, inconsistency and imprecision). 42 44 45

You present the results to your patient ( table 3 shows results of select outcomes from the NutriRECS systematic reviews of cohort studies 43–45 ). Given the uncertainty (low to very certainty evidence) and small to very small magnitude of any benefit of reducing consumption (by three servings/week) that might exist, the patient considers the inconvenience and reduction in the pleasure of eating not worth the possible benefits and chooses to continue her current levels of red and processed meat consumption, meats that come from local, regenerative and ethical farming practices.

Summary of select findings of the NutriRECS systematic reviews

Ethics statements

Patient consent for publication.

Not applicable.

Ethics approval

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X @DenaZera, @PabloACoello, @methodsnerd

Contributors DZ, BCJ and GHG conceptualised the paper. DZ and BCJ drafted the paper. RJdS, GHG, MMB, and PA-C provided critical feedback. DZ, MMB, PA-C, RJdS, GHG and BCJ revised the paper. DZ and BCJ provided technical support. All authors reviewed the semi-final version and approved the final version for publication. DZ and BCJ are guarators.

Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests GHG, BCJ, MMB, PA-C and DZ are GRADE working group members. BCJ has received a start-up grant from Texas A&M AgriLife Research to fund investigator-initiated research related to saturated and polyunsaturated fats. The grant was from Texas A&M AgriLife institutional funds from interest and investment earnings, not a sponsoring organisation, industry or company. BCJ also holds National Institute of Diabetes, Digestive and Kidney Diseases R25 funds to support training in evidence-based nutrition practice. Other authors claim no disclosures.

Provenance and peer review Not commissioned; externally peer reviewed.

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not all literature ‘reviews’ are the same

I was trying to explain to a doctoral researcher the other day that the literature work that you do at the beginning of the doctorate is not the same as the literature work for the actual, final thesis that is handed up. I was doing a Not Very Good Job of this explanation when I remembered the book Doing your literature review. Traditional and systematic techniques , by Jesson, Matheson and Lacey (Sage 2011).

Jesson and her colleagues suggest that there are two basic types of literature review – they use the term review so I will too – the traditional and the systematic . I’ve adapted what they have to say in the following account and the argument I’m making is mine, not theirs. It’s the point I was trying unsuccessfully to make with the doctoral researcher.

The systematic review is what is also sometimes called an evidence-based review. It applies measures of the ’quality’ of research as a way of filtering and evaluating what texts are included and excluded. According to Jesson, Matheson and Lacey, the systematic review’s hierarchy of research usually has randomized controlled trials and meta-analysis at the top, followed by other quantitative studies such as cohort studies and surveys. Then follows various forms of qualitative research; these are generally, but not always, omitted from systematic reviews. The decision about what comes on top of the quality hierarchy is of course highly contentious, and there are lots of published debates about it. I don’t intend to canvass those here, just to understand this as a type of review.

The traditional review by contrast is usually based on a critical assessment of a personal selection of material and has different purposes. Jesson and colleagues offer five different variants of the traditional review. None of these are completely separate, in fact they overlap quite considerably. Nevertheless, there are some discernable differences in purpose and process.

The five types of traditional literature review are :

(1) a conceptual review . This synthesises and critically assesses literature to see the way in which a particular issue is understood. The conceptual review might also examine how the issue is researched, how those understandings are produced. The purpose of the conceptual review is to produce a greater understanding of the issue.

(2) a state-of the-art review . This examines the most recent contributions to a field or area of study in the light of its history of research. It particularly looks for trends, agreements, and debates. This is the kind of review that editors of journals write at periodic intervals in order to position their journal and its future directions.

(3) an expert review . Rather like the state-of-the-art review, but undertaken by a senior figure in the field and heavily inflected with their own particular interests and contributions. This is the kind of review that presidents of learned societies give to the assembled masses at a conference.

Now the next variation is the one that is undertaken at the start of the doctorate or in a research bid in order to position the new research project: (4) the scoping review. This review sets out to create an agenda for future research. It documents what is already known about a topic, and then focuses on the gaps, niches, disputes, blank and blind spots. It delineates key concepts, questions and theories in order to refine the research question(s) and justify an approach to be taken.

The final variation is the literature review as it appears in the final humanities/social science thesis or in a journal article or book, after the research has been completed. (5) the traditional review. This is somewhat like a scoping review, but its argument is not to create the space for a research project. It is to position a piece of research that has already been undertaken. In essence the reader gets what’s-already-known, plus the newly conducted piece – this research as the contribution. The literature is used to locate the contribution, the what-we-now-know-that-we-didn’t-before-and-why-this-is-important. Some texts and themes that were in the initial scoping review are omitted, and other things are now emphasized in order to make clear the connections and continuities, similarities and differences of the new research to what’s gone before.

So, (4) scoping and (5) traditional just don’t do the same job. They are different in purposes. One justifies the research to be done, the other locates the contribution in the field of completed research.

The obvious implication of this difference is that y ou can’t just dump the literature work you did for the proposal in the thesis text . You have to do more work on the literature when you are writing the thesis. It has to be modified in some way from what you did at the outset. Not just because you’ve read more since you started, but because the argument is somewhat different.

Well you can, and some do, just cut and paste the proposal literatures into the final dissertation text – and there’s nothing wrong with using the proposal as a kind of ‘holding text’ while you’re working on the results. However, there are consequences for not changing it before submission. The lack of awareness of the difference between beginning=scoping and end=traditional literature work is often why examiners ask people to write more/write again.

And we don’t want that – neither doctoral researcher, nor their supervisor!

Jill K Jesson with Lydia Matheson and Fiona M Lacey (2011) Doing your literature review. Traditional and systematic techniques . Los Angeles: Sage (pp 76, 117)

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15 responses to not all literature ‘reviews’ are the same.

This is an excellent post for student researchers and their supervisors. I have always struggled with helping students to write a proper literature review. This helps.

Thank you! I think I’m a #4, Julia

Reblogged this on Lectio Divina, or daily seeings .

This a good food for thought at all stages of engaging with literature review in my struggle for PhD proposal writing for some time now. Tough time.

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Academic Phrases for Writing Literature Review Section of a Research Paper

Overview |   Abstract   | Introduction | Literature Review | Materials & Methods | Results & Discussion | Conclusion & Future Work | Acknowledgements & Appendix

The literature review should clearly demonstrate that the author has a good knowledge of the research area. Literature review typically occupies one or two passages in the introduction section. A well-written literature review should provide a critical appraisal of previous studies related to the current research area rather than a simple summary of prior works. The author shouldn’t shy away from pointing out the shortcomings of previous works. However, criticising other’s work without any basis can weaken your paper. This is a perfect place to coin your research question and justify the need for such a study. It is also worth pointing out towards the end of the review that your study is unique and there is no direct literature addressing this issue. Add a few sentences about the significance of your research and how this will add value to the body of knowledge.

The literature review section of your research paper should include the following:

• Previous literature
• Limitations of previous research
• Research questions
• Research to be explored

1. Previous literature

The literature review shows that __ Previous research showed __ Seminal contributions have been made by __ A series of recent studies has indicated that __ Several theories have been proposed to __, some focusing on __, others on __ There has been numerous studies to investigate __ This has been used in several studies to assess __ Previous studies have shown __ Several studies suggest that __ This has also been explored in prior studies by __ Prior research suggests that __ Previous studies have emphasized __ The majority of prior research has applied __ Most early studies as well as current work focus on __ For instance, the following studies were conducted on __ Studies of __are well documented, it is also well acknowledged that __ A number of authors have recognized __ Some authors have also suggested that  __ Some authors have driven the further development of __ This has been discussed by a great number of authors in literature. For example, research has provided evidence for __ The authors bring some information about the background of the problem, __ As has been previously reported in the literature, __ A large number of existing studies in the broader literature have examined __ The literature review shows that __ There exists a considerable body of literature on  __ In short, the literature pertaining to __ strongly suggests that __ Over time, an extensive literature has developed on __ This section presents a review of recent literature on __ This paper begins with a short review of the literature regarding the __ Several methods are reported in the literature to address this issue. There is a wide choice of __ available in the literature. This section reviews the literature related to __ It was reported in literature that __ A recent study by __ concluded that __ In the light of reported __ it is conceivable that __ The method introduced by __ has the advantage that __ One method employed by __ is __ A more comprehensive description can be found in __ For example, recent research suggests that __ This was successfully established as described by __ The author employed a __ methodology which prescribes the use of __

2. Limitations of previous research

A number of questions regarding __ remain to be addressed. A closer look to the literature on __, however, reveals a number of gaps and shortcomings. This question has previously never been addressed because__ Most studies have relied on __ Previous studies by __ cannot be considered as conclusive because __ Previous studies have almost exclusively focused on __ This has been previously assessed only to a very limited extent because __ In the present studies __ were constrained to __ In previous studies were limited to __ Although results appear consistent with prior research, they appear inconsistent with __ These are previously unstudied because __ As far as we know, no previous research has investigated __ Moreover, although research has illuminated __ no study to date has examined __ Despite decades of research, this continues to be debated among __ This section points out some of the problems encountered in the extant research. Although there are many studies, the research in __ remains limited. However, the existing research has many problems in representing __ The literature on __ is less consistent Historically, there has been a great deal of confusion in the literature regarding __ This approach remains briefly addressed in the literature. These are rarely analyzed in the literature as __ There are key questions and notions that are still not discussed in the literature __ This is not clearly presented in the literature because __ This paper addresses the need for __, so far lacking in the scientific literature. To fill this literature gap, this paper identifies __ Only a few works in literature demonstrate __ Although studies have been conducted by many authors, this problem is still insufficiently explored. To our knowledge, no prior studies have examined __ However, the existing research has many problems in __ Therefore, important issue in the literature is __ However, we argue that previous literature suffers from certain weaknesses: __ Previous research can only be considered a first step towards a more profound understanding of __ The previous studies reveal that __ are usually the most problematic to __

3. Research questions

More specific research questions will be introduced and investigated in __ A further question is whether __ Finally, another promising line of research would be __ The study addresses several further questions on __ Some of the interesting questions in this context are __ In order to address the questions outlined above, we report here __ These questions are of central interest as much recent research in __ Furthermore, __ is arguably an important question to be addressed. The question now is how __ can be used to explain __ Study addresses the research question __ In order to properly address this question, we __ An important question associated with __ is __ A critical open question is whether __ A still unsolved question is whether __ This remains an open question as __ This question has previously never been addressed because __ This study offers a test of __ research question Study addresses the research question __ Even in general __ research strategies is needed to explain __ The researcher should be interested here in __ Many questions remain unanswered __ There are some potentially open questions about the validity of __ The question that then naturally arises is __ The question then becomes how best to define__ This was an important question to study as __

4. Research to be explored

A more systematic and theoretical analysis is required for __ As the authors note earlier, more work is necessary to__ Additional studies to understand more completely the key tenets of __ are required. The unexpected findings signal the need for additional studies to understand more about __ This paper addresses __, so far lacking in the scientific literature. A new approach is therefore needed for __ One of the tough challenges for all researchers in this domain is __

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Applications and performance of precision id globalfiler ngs str, identity, and ancestry panels in forensic genetics.

1. Introduction

2. materials and methods, 4. discussion, 4.1. contributions by country, 4.2. contributions by year, 4.3. articles type, journal, and access, 4.4. articles focus and current knowledge, 4.4.1. precision id globalfiler ngs str panel, 4.4.2. precision id identity panel, 4.4.3. precision id ancestry panel, 4.5. sequencing instrument and automation, 4.6. limitations, 4.7. future perspectives, 4.8. ethical considerations, 5. conclusions, author contributions, data availability statement, conflicts of interest.

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Share and Cite

Pedroza Matute, S.; Iyavoo, S. Applications and Performance of Precision ID GlobalFiler NGS STR, Identity, and Ancestry Panels in Forensic Genetics. Genes 2024 , 15 , 1133. https://doi.org/10.3390/genes15091133

Pedroza Matute S, Iyavoo S. Applications and Performance of Precision ID GlobalFiler NGS STR, Identity, and Ancestry Panels in Forensic Genetics. Genes . 2024; 15(9):1133. https://doi.org/10.3390/genes15091133

Pedroza Matute, Sharlize, and Sasitaran Iyavoo. 2024. "Applications and Performance of Precision ID GlobalFiler NGS STR, Identity, and Ancestry Panels in Forensic Genetics" Genes 15, no. 9: 1133. https://doi.org/10.3390/genes15091133

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Wellness Wednesday - Some Useful AI Literature Review Tools

Hi everyone,

I have been playing with a few new AI tools for literature reviews that you might like, especially Semantic Scholar which is like Google Scholar on steroids.

Semantic Scholar https://semanticscholar.org

Scite AI https://scite.ai

Connected Papers https://connectedpapers.com

I also recorded a YouTube video looking at some of the features of each on my YouTube channel.

I hope you find them useful.

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Blog The Education Hub

https://educationhub.blog.gov.uk/2024/08/20/gcse-results-day-2024-number-grading-system/

GCSE results day 2024: Everything you need to know including the number grading system

Thousands of students across the country will soon be finding out their GCSE results and thinking about the next steps in their education.   

Here we explain everything you need to know about the big day, from when results day is, to the current 9-1 grading scale, to what your options are if your results aren’t what you’re expecting.  

When is GCSE results day 2024?  

GCSE results day will be taking place on Thursday the 22 August.     

The results will be made available to schools on Wednesday and available to pick up from your school by 8am on Thursday morning.  

Schools will issue their own instructions on how and when to collect your results.   

When did we change to a number grading scale?  

The shift to the numerical grading system was introduced in England in 2017 firstly in English language, English literature, and maths.  

By 2020 all subjects were shifted to number grades. This means anyone with GCSE results from 2017-2020 will have a combination of both letters and numbers.  

The numerical grading system was to signal more challenging GCSEs and to better differentiate between students’ abilities - particularly at higher grades between the A *-C grades. There only used to be 4 grades between A* and C, now with the numerical grading scale there are 6.  

What do the number grades mean?  

The grades are ranked from 1, the lowest, to 9, the highest.  

The grades don’t exactly translate, but the two grading scales meet at three points as illustrated below.  

The bottom of grade 7 is aligned with the bottom of grade A, while the bottom of grade 4 is aligned to the bottom of grade C.    

Meanwhile, the bottom of grade 1 is aligned to the bottom of grade G.  

What to do if your results weren’t what you were expecting?  

If your results weren’t what you were expecting, firstly don’t panic. You have options.  

First things first, speak to your school or college – they could be flexible on entry requirements if you’ve just missed your grades.   

They’ll also be able to give you the best tailored advice on whether re-sitting while studying for your next qualifications is a possibility.   

If you’re really unhappy with your results you can enter to resit all GCSE subjects in summer 2025. You can also take autumn exams in GCSE English language and maths.  

Speak to your sixth form or college to decide when it’s the best time for you to resit a GCSE exam.  

Look for other courses with different grade requirements     

Entry requirements vary depending on the college and course. Ask your school for advice, and call your college or another one in your area to see if there’s a space on a course you’re interested in.    

Consider an apprenticeship    

Apprenticeships combine a practical training job with study too. They’re open to you if you’re 16 or over, living in England, and not in full time education.  

As an apprentice you’ll be a paid employee, have the opportunity to work alongside experienced staff, gain job-specific skills, and get time set aside for training and study related to your role.   

You can find out more about how to apply here .  

Talk to a National Careers Service (NCS) adviser    

The National Career Service is a free resource that can help you with your career planning. Give them a call to discuss potential routes into higher education, further education, or the workplace.   

Whatever your results, if you want to find out more about all your education and training options, as well as get practical advice about your exam results, visit the  National Careers Service page  and Skills for Careers to explore your study and work choices.   

You may also be interested in:

• Results day 2024: What's next after picking up your A level, T level and VTQ results?
• When is results day 2024? GCSEs, A levels, T Levels and VTQs

Tags: GCSE grade equivalent , gcse number grades , GCSE results , gcse results day 2024 , gsce grades old and new , new gcse grades

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Citing and Referencing

University  , harvard referencing, professional development  , human resources management, quizizz test lesson, types of essays, writing a cover letter, 10th -  11th  , academic integrity, blooms taxonomy.

literature review (1)

12th - university, professional development.

12 questions

Introducing new   Paper mode

No student devices needed.   Know more

• When starting literature review what is the first step?

a. Identifying the research question

b. Finding articles

c. Planning the study

d. Finding websites

Which of the following sentences in not true about the purpose of doing literature review?

a. to learn about the existing information about a given topic

b. to better formulate the research question

c. to critically analyse the concept being studied

d. to provide a summary of what has been written about a given topic

Which of the following is not a good research question?

a. What can be done to help the homeless find permanent shelters?

b. What are the effects of online social networking on children?

c. What can be done to make video games less harmful?

d. Is there a relationship between length of sleep and obesity?

Which of the following approaches to reading do you think is not useful in literature review?

a. Memorizing

b. Evaluating

c. Comparing

Where do you start when conducting literature review?

a. Scanning the source

b. Skimming the source

c. Analysing the information

d. Critiquing the information

If you believe you will use the information from a source, what should you do?

a. Make note of the information I think I will use.

b. Add the information about the book to my reference list.

c. Write my comments about the information next to my notes.

d. All of the above

• Which is most probably not a suitable source to use in an academic literature review?

b. Reference book

c. Journal article

d. Online article

Is this a good academic research topic? "What is the role of advertising in the world?"

a. No. It is too broad.

b. No It is too narrow

c. Yes. It is a good research topic.

d. No. It is leading.

• Which of the following is not plagiarism?

a. Translating a source and using it without mentioning the source

b. Using an image found on the Internet without mentioning the source

c. Using common knowledge with out mentioning the source

d. Summarising someone's work without mentioning the source

Which of the following is not true about index of a book?

a. Index is organised alphabetically.

b. Page number is provided in the index list.

c. It is provided at the beginning of a book.

d. It is helpful to use index of a book when looking for books to review.

Abstract ...

a. is a brief summary of a research article.

b. cannot be cited.

c. is written before an article is written.

d. is not useful when reviewing literature.

• The research question

a. had better be general.

b. cannot be modified during literature review.

c. is not necessary when you begin the research.

d. will guide the literature search.

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