poor literature review example

Eight problems with literature reviews and how to fix them

Affiliations.

• 1 Mercator Research Institute on Climate Change and Global Commons, Berlin, Germany. [email protected].
• 2 Stockholm Environment Institute, Stockholm, Sweden. [email protected].
• 3 Africa Centre for Evidence, University of Johannesburg, Johannesburg, South Africa. [email protected].
• 4 College of Medicine and Health, Exeter University, Exeter, UK.
• 5 Department of Zoology, University of Cambridge, Cambridge, UK.
• 6 School of Biological Sciences, University of East Anglia, Norwich, UK.
• 7 Department of Biological Sciences, Royal Holloway University of London, Egham, UK.
• 8 Stockholm Environment Institute, Stockholm, Sweden.
• 9 Department of Zoology, University of Oxford, Oxford, UK.
• 10 Collaboration for Environmental Evidence, UK Centre, School of Natural Sciences, Bangor University, Bangor, UK.
• 11 Liljus ltd, London, UK.
• 12 Department of Forest Sciences, University of Helsinki, Helsinki, Finland.
• 13 Evidence Synthesis Lab, School of Natural and Environmental Sciences, University of Newcastle, Newcastle-upon-Tyne, UK.
• PMID: 33046871
• DOI: 10.1038/s41559-020-01295-x

Traditional approaches to reviewing literature may be susceptible to bias and result in incorrect decisions. This is of particular concern when reviews address policy- and practice-relevant questions. Systematic reviews have been introduced as a more rigorous approach to synthesizing evidence across studies; they rely on a suite of evidence-based methods aimed at maximizing rigour and minimizing susceptibility to bias. Despite the increasing popularity of systematic reviews in the environmental field, evidence synthesis methods continue to be poorly applied in practice, resulting in the publication of syntheses that are highly susceptible to bias. Recognizing the constraints that researchers can sometimes feel when attempting to plan, conduct and publish rigorous and comprehensive evidence syntheses, we aim here to identify major pitfalls in the conduct and reporting of systematic reviews, making use of recent examples from across the field. Adopting a 'critical friend' role in supporting would-be systematic reviews and avoiding individual responses to police use of the 'systematic review' label, we go on to identify methodological solutions to mitigate these pitfalls. We then highlight existing support available to avoid these issues and call on the entire community, including systematic review specialists, to work towards better evidence syntheses for better evidence and better decisions.

• Environment
• Research Design
• Systematic Reviews as Topic*

Eight common problems with science literature reviews and how to fix them

Research Fellow, Africa Centre for Evidence, University of Johannesburg

Disclosure statement

Neal Robert Haddaway works for the Stockholm Environment Institute and the Mercator Research Institute on Global Commons and Climate Change. He receives funding from the Alexander von Humboldt Foundation, Mistra, Formas, and Vinnova. He is also an honorary Research Associate at the Africa Centre for Evidence at the University of Johannesburg.

University of Johannesburg provides support as an endorsing partner of The Conversation AFRICA.

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Researchers regularly review the literature that’s generated by others in their field. This is an integral part of day-to-day research: finding relevant research, reading and digesting the main findings, summarising across papers, and making conclusions about the evidence base as a whole.

However, there is a fundamental difference between brief, narrative approaches to summarising a selection of studies and attempting to reliably, comprehensively summarise an evidence base to support decision-making in policy and practice.

So-called “evidence-informed decision-making” relies on rigorous systematic approaches to synthesising the evidence. Systematic review has become the highest standard of evidence synthesis. It is well established in the pipeline from research to practice in several fields including health , the environment and social policy . Rigorous systematic reviews are vital for decision-making because they help to provide the strongest evidence that a policy is likely to work (or not). They also help to avoid expensive or dangerous mistakes in the choice of policies.

But systematic review has not yet entirely replaced traditional methods of literature review. These traditional reviews may be susceptible to bias and so may end up providing incorrect conclusions. This is especially worrying when reviews address key policy and practice questions.

The good news is that the limitations of traditional literature review approaches could be improved relatively easily with a few key procedures. Some of these are not prohibitively costly in terms of skill, time or resources. That’s particularly important in African contexts, where resource constraints are a daily reality, but should not compromise the continent’s need for rigorous, systematic and transparent evidence to inform policy.

In our recent paper in Nature Ecology and Evolution , we highlighted eight common problems with traditional literature review methods. We gave examples for each problem, drawing from the field of environmental management and ecology. Finally, we outlined practical solutions.

These are the eight problems we identified in our paper .

First, traditional literature reviews can lack relevance. This is because limited stakeholder engagement can lead to a review that is of limited practical use to decision-makers.

Second, reviews that don’t publish their methods in an a priori (meaning that it is published before the review work begins) protocol may suffer from mission creep. In our paper we give the example of a 2019 review that initially stated it was looking at all population trends among insects. Instead, it ended up focusing only on studies that showed insect population declines. This could have been prevented by publishing and sticking to methods outlined in a protocol.

Third, a lack of transparency and replicability in the review methods may mean that the review cannot be replicated . Replicability is a central tenet of the scientific method.

Selection bias is another common problem. Here, the studies that are included in a literature review are not representative of the evidence base. A lack of comprehensiveness, stemming from an inappropriate search method, can also mean that reviews end up with the wrong evidence for the question at hand.

Traditional reviews may also exclude grey literature . This is defined as any document

produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers, i.e., where publishing is not the primary activity of the producing body.

It includes organisational reports and unpublished theses or other studies . Traditional reviews may also fail to test for evidence of publication bias; both these issues can result in incorrect or misleading conclusions. Another common error is to treat all evidence as equally valid. The reality is that some research studies are more valid than others. This needs to be accounted for in the synthesis.

Inappropriate synthesis is another common issue. This involves methods like vote-counting, which refers to tallying studies based on their statistical significance. Finally, a lack of consistency and error checking (as would happen when a reviewer works alone) can introduce errors and biases if a single reviewer makes decisions without consensus .

All of these common problems can be solved, though. Here’s how.

Stakeholders can be identified, mapped and contacted for feedback and inclusion without the need for extensive budgets. Best-practice guidelines for this process already exist .

Researchers can carefully design and publish an a priori protocol that outlines planned methods for searching, screening, data extraction, critical appraisal and synthesis in detail. Organisations like the Collaboration for Environmental Evidence have existing protocols from which people can draw.

Researchers also need to be explicit and use high-quality guidance and standards for review conduct and reporting . Several such standards already exist .

Another useful approach is to carefully design a search strategy with an info specialist; to trial the search strategy against a benchmark list; and to use multiple bibliographic databases, languages and sources of grey literature. Researchers should then publish their search methods in an a priori protocol for peer review.

Researchers should consider carefully planning and trialling a critical appraisal tool before starting the process in full, learning from existing robust critical appraisal tools . Critical appraisal is the carefully planned assessment of all possible risks of bias and possible confounders in a research study. Researchers should select their synthesis method carefully, based on the data analysed. Vote-counting should never be used instead of meta-analysis. Formal methods for narrative synthesis should be used to summarise and describe the evidence base.

Finally, at least two reviewers should screen a subset of the evidence base to ensure consistency and shared understanding of the methods before proceeding. Ideally, reviewers should conduct all decisions separately and then consolidate.

Collaboration

Collaboration is crucial to address the problems with traditional review processes. Authors need to conduct more rigorous reviews. Editors and peer reviewers need to gate-keep more strictly. The community of methodologists needs to better support the broader research community.

Working together, the academic and research community can build and maintain a strong system of rigorous, evidence-informed decision-making in conservation and environmental management – and, ultimately, in other disciplines.

• Systematic reviews
• Evidence based policy
• Academic research

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• Published: 12 October 2020

Eight problems with literature reviews and how to fix them

• Neal R. Haddaway   ORCID: orcid.org/0000-0003-3902-2234 1 , 2 , 3 ,
• Alison Bethel 4 ,
• Lynn V. Dicks 5 , 6 ,
• Julia Koricheva   ORCID: orcid.org/0000-0002-9033-0171 7 ,
• Biljana Macura   ORCID: orcid.org/0000-0002-4253-1390 2 ,
• Gillian Petrokofsky 8 ,
• Andrew S. Pullin 9 ,
• Sini Savilaakso   ORCID: orcid.org/0000-0002-8514-8105 10 , 11 &
• Gavin B. Stewart   ORCID: orcid.org/0000-0001-5684-1544 12  

Nature Ecology & Evolution volume  4 ,  pages 1582–1589 ( 2020 ) Cite this article

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• Conservation biology
• Environmental impact

An Author Correction to this article was published on 19 October 2020

This article has been updated

Traditional approaches to reviewing literature may be susceptible to bias and result in incorrect decisions. This is of particular concern when reviews address policy- and practice-relevant questions. Systematic reviews have been introduced as a more rigorous approach to synthesizing evidence across studies; they rely on a suite of evidence-based methods aimed at maximizing rigour and minimizing susceptibility to bias. Despite the increasing popularity of systematic reviews in the environmental field, evidence synthesis methods continue to be poorly applied in practice, resulting in the publication of syntheses that are highly susceptible to bias. Recognizing the constraints that researchers can sometimes feel when attempting to plan, conduct and publish rigorous and comprehensive evidence syntheses, we aim here to identify major pitfalls in the conduct and reporting of systematic reviews, making use of recent examples from across the field. Adopting a ‘critical friend’ role in supporting would-be systematic reviews and avoiding individual responses to police use of the ‘systematic review’ label, we go on to identify methodological solutions to mitigate these pitfalls. We then highlight existing support available to avoid these issues and call on the entire community, including systematic review specialists, to work towards better evidence syntheses for better evidence and better decisions.

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Acknowledgements

We thank C. Shortall from Rothamstead Research for useful discussions on the topic.

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Neal R. Haddaway

Stockholm Environment Institute, Stockholm, Sweden

Neal R. Haddaway & Biljana Macura

Africa Centre for Evidence, University of Johannesburg, Johannesburg, South Africa

College of Medicine and Health, Exeter University, Exeter, UK

Alison Bethel

Department of Zoology, University of Cambridge, Cambridge, UK

Lynn V. Dicks

School of Biological Sciences, University of East Anglia, Norwich, UK

Department of Biological Sciences, Royal Holloway University of London, Egham, UK

Julia Koricheva

Department of Zoology, University of Oxford, Oxford, UK

Gillian Petrokofsky

Collaboration for Environmental Evidence, UK Centre, School of Natural Sciences, Bangor University, Bangor, UK

Andrew S. Pullin

Liljus ltd, London, UK

Sini Savilaakso

Department of Forest Sciences, University of Helsinki, Helsinki, Finland

Evidence Synthesis Lab, School of Natural and Environmental Sciences, University of Newcastle, Newcastle-upon-Tyne, UK

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Haddaway, N.R., Bethel, A., Dicks, L.V. et al. Eight problems with literature reviews and how to fix them. Nat Ecol Evol 4 , 1582–1589 (2020). https://doi.org/10.1038/s41559-020-01295-x

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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.

Literature Review Example/Sample

Detailed Walkthrough + Free Literature Review Template

If you’re working on a dissertation or thesis and are looking for an example of a strong literature review chapter , you’ve come to the right place.

In this video, we walk you through an A-grade literature review from a dissertation that earned full distinction . We start off by discussing the five core sections of a literature review chapter by unpacking our free literature review template . This includes:

• The literature review opening/ introduction section
• The theoretical framework (or foundation of theory)
• The empirical research
• The research gap
• The closing section

We then progress to the sample literature review (from an A-grade Master’s-level dissertation) to show how these concepts are applied in the literature review chapter. You can access the free resources mentioned in this video below.

PS – If you’re working on a dissertation, be sure to also check out our collection of dissertation and thesis examples here .

FAQ: Literature Review Example

Literature review example: frequently asked questions, is the sample literature review real.

Yes. The literature review example is an extract from a Master’s-level dissertation for an MBA program. It has not been edited in any way.

Can I replicate this literature review for my dissertation?

As we discuss in the video, every literature review will be slightly different, depending on the university’s unique requirements, as well as the nature of the research itself. Therefore, you’ll need to tailor your literature review to suit your specific context.

You can learn more about the basics of writing a literature review here .

Where can I find more examples of literature reviews?

The best place to find more examples of literature review chapters would be within dissertation/thesis databases. These databases include dissertations, theses and research projects that have successfully passed the assessment criteria for the respective university, meaning that you have at least some sort of quality assurance. 

The Open Access Thesis Database (OATD) is a good starting point. 

How do I get the literature review template?

You can access our free literature review chapter template here .

Is the template really free?

Yes. There is no cost for the template and you are free to use it as you wish. 

Psst… there’s more!

This post is an extract from our bestselling short course, Literature Review Bootcamp . If you want to work smart, you don't want to miss this .

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Literature Review: Conducting & Writing

• Sample Literature Reviews
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15 Literature Review Examples

Literature reviews are a necessary step in a research process and often required when writing your research proposal . They involve gathering, analyzing, and evaluating existing knowledge about a topic in order to find gaps in the literature where future studies will be needed.

Ideally, once you have completed your literature review, you will be able to identify how your research project can build upon and extend existing knowledge in your area of study.

Generally, for my undergraduate research students, I recommend a narrative review, where themes can be generated in order for the students to develop sufficient understanding of the topic so they can build upon the themes using unique methods or novel research questions.

If you’re in the process of writing a literature review, I have developed a literature review template for you to use – it’s a huge time-saver and walks you through how to write a literature review step-by-step:

Get your time-saving templates here to write your own literature review.

Literature Review Examples

For the following types of literature review, I present an explanation and overview of the type, followed by links to some real-life literature reviews on the topics.

1. Narrative Review Examples

Also known as a traditional literature review, the narrative review provides a broad overview of the studies done on a particular topic.

It often includes both qualitative and quantitative studies and may cover a wide range of years.

The narrative review’s purpose is to identify commonalities, gaps, and contradictions in the literature .

I recommend to my students that they should gather their studies together, take notes on each study, then try to group them by themes that form the basis for the review (see my step-by-step instructions at the end of the article).

Example Study

Title: Communication in healthcare: a narrative review of the literature and practical recommendations

Citation: Vermeir, P., Vandijck, D., Degroote, S., Peleman, R., Verhaeghe, R., Mortier, E., … & Vogelaers, D. (2015). Communication in healthcare: a narrative review of the literature and practical recommendations. International journal of clinical practice , 69 (11), 1257-1267.

Source: https://onlinelibrary.wiley.com/doi/pdf/10.1111/ijcp.12686  

Overview: This narrative review analyzed themes emerging from 69 articles about communication in healthcare contexts. Five key themes were found in the literature: poor communication can lead to various negative outcomes, discontinuity of care, compromise of patient safety, patient dissatisfaction, and inefficient use of resources. After presenting the key themes, the authors recommend that practitioners need to approach healthcare communication in a more structured way, such as by ensuring there is a clear understanding of who is in charge of ensuring effective communication in clinical settings.

Other Examples

• Burnout in United States Healthcare Professionals: A Narrative Review (Reith, 2018) – read here
• Examining the Presence, Consequences, and Reduction of Implicit Bias in Health Care: A Narrative Review (Zestcott, Blair & Stone, 2016) – read here
• A Narrative Review of School-Based Physical Activity for Enhancing Cognition and Learning (Mavilidi et al., 2018) – read here
• A narrative review on burnout experienced by medical students and residents (Dyrbye & Shanafelt, 2015) – read here

2. Systematic Review Examples

This type of literature review is more structured and rigorous than a narrative review. It involves a detailed and comprehensive plan and search strategy derived from a set of specified research questions.

The key way you’d know a systematic review compared to a narrative review is in the methodology: the systematic review will likely have a very clear criteria for how the studies were collected, and clear explanations of exclusion/inclusion criteria. 

The goal is to gather the maximum amount of valid literature on the topic, filter out invalid or low-quality reviews, and minimize bias. Ideally, this will provide more reliable findings, leading to higher-quality conclusions and recommendations for further research.

You may note from the examples below that the ‘method’ sections in systematic reviews tend to be much more explicit, often noting rigid inclusion/exclusion criteria and exact keywords used in searches.

Title: The importance of food naturalness for consumers: Results of a systematic review  

Citation: Roman, S., Sánchez-Siles, L. M., & Siegrist, M. (2017). The importance of food naturalness for consumers: Results of a systematic review. Trends in food science & technology , 67 , 44-57.

Source: https://www.sciencedirect.com/science/article/pii/S092422441730122X  

Overview: This systematic review included 72 studies of food naturalness to explore trends in the literature about its importance for consumers. Keywords used in the data search included: food, naturalness, natural content, and natural ingredients. Studies were included if they examined consumers’ preference for food naturalness and contained empirical data. The authors found that the literature lacks clarity about how naturalness is defined and measured, but also found that food consumption is significantly influenced by perceived naturalness of goods.

• A systematic review of research on online teaching and learning from 2009 to 2018 (Martin, Sun & Westine, 2020) – read here
• Where Is Current Research on Blockchain Technology? (Yli-Huumo et al., 2016) – read here
• Universities—industry collaboration: A systematic review (Ankrah & Al-Tabbaa, 2015) – read here
• Internet of Things Applications: A Systematic Review (Asghari, Rahmani & Javadi, 2019) – read here

3. Meta-analysis

This is a type of systematic review that uses statistical methods to combine and summarize the results of several studies.

Due to its robust methodology, a meta-analysis is often considered the ‘gold standard’ of secondary research , as it provides a more precise estimate of a treatment effect than any individual study contributing to the pooled analysis.

Furthermore, by aggregating data from a range of studies, a meta-analysis can identify patterns, disagreements, or other interesting relationships that may have been hidden in individual studies.

This helps to enhance the generalizability of findings, making the conclusions drawn from a meta-analysis particularly powerful and informative for policy and practice.

Title: Cholesterol and Alzheimer’s Disease Risk: A Meta-Meta-Analysis

Citation: Sáiz-Vazquez, O., Puente-Martínez, A., Ubillos-Landa, S., Pacheco-Bonrostro, J., & Santabárbara, J. (2020). Cholesterol and Alzheimer’s disease risk: a meta-meta-analysis. Brain sciences, 10(6), 386.

Source: https://doi.org/10.3390/brainsci10060386  

O verview: This study examines the relationship between cholesterol and Alzheimer’s disease (AD). Researchers conducted a systematic search of meta-analyses and reviewed several databases, collecting 100 primary studies and five meta-analyses to analyze the connection between cholesterol and Alzheimer’s disease. They find that the literature compellingly demonstrates that low-density lipoprotein cholesterol (LDL-C) levels significantly influence the development of Alzheimer’s disease.

• The power of feedback revisited: A meta-analysis of educational feedback research (Wisniewski, Zierer & Hattie, 2020) – read here
• How Much Does Education Improve Intelligence? A Meta-Analysis (Ritchie & Tucker-Drob, 2018) – read here
• A meta-analysis of factors related to recycling (Geiger et al., 2019) – read here
• Stress management interventions for police officers and recruits (Patterson, Chung & Swan, 2014) – read here

Other Types of Reviews

• Scoping Review: This type of review is used to map the key concepts underpinning a research area and the main sources and types of evidence available. It can be undertaken as stand-alone projects in their own right, or as a precursor to a systematic review.
• Rapid Review: This type of review accelerates the systematic review process in order to produce information in a timely manner. This is achieved by simplifying or omitting stages of the systematic review process.
• Integrative Review: This review method is more inclusive than others, allowing for the simultaneous inclusion of experimental and non-experimental research. The goal is to more comprehensively understand a particular phenomenon.
• Critical Review: This is similar to a narrative review but requires a robust understanding of both the subject and the existing literature. In a critical review, the reviewer not only summarizes the existing literature, but also evaluates its strengths and weaknesses. This is common in the social sciences and humanities .
• State-of-the-Art Review: This considers the current level of advancement in a field or topic and makes recommendations for future research directions. This type of review is common in technological and scientific fields but can be applied to any discipline.

How to Write a Narrative Review (Tips for Undergrad Students)

Most undergraduate students conducting a capstone research project will be writing narrative reviews. Below is a five-step process for conducting a simple review of the literature for your project.

• Search for Relevant Literature: Use scholarly databases related to your field of study, provided by your university library, along with appropriate search terms to identify key scholarly articles that have been published on your topic.
• Evaluate and Select Sources: Filter the source list by selecting studies that are directly relevant and of sufficient quality, considering factors like credibility , objectivity, accuracy, and validity.
• Analyze and Synthesize: Review each source and summarize the main arguments  in one paragraph (or more, for postgrad). Keep these summaries in a table.
• Identify Themes: With all studies summarized, group studies that share common themes, such as studies that have similar findings or methodologies.
• Write the Review: Write your review based upon the themes or subtopics you have identified. Give a thorough overview of each theme, integrating source data, and conclude with a summary of the current state of knowledge then suggestions for future research based upon your evaluation of what is lacking in the literature.

Literature reviews don’t have to be as scary as they seem. Yes, they are difficult and require a strong degree of comprehension of academic studies. But it can be feasibly done through following a structured approach to data collection and analysis. With my undergraduate research students (who tend to conduct small-scale qualitative studies ), I encourage them to conduct a narrative literature review whereby they can identify key themes in the literature. Within each theme, students can critique key studies and their strengths and limitations , in order to get a lay of the land and come to a point where they can identify ways to contribute new insights to the existing academic conversation on their topic.

Ankrah, S., & Omar, A. T. (2015). Universities–industry collaboration: A systematic review. Scandinavian Journal of Management, 31(3), 387-408.

Asghari, P., Rahmani, A. M., & Javadi, H. H. S. (2019). Internet of Things applications: A systematic review. Computer Networks , 148 , 241-261.

Dyrbye, L., & Shanafelt, T. (2016). A narrative review on burnout experienced by medical students and residents. Medical education , 50 (1), 132-149.

Geiger, J. L., Steg, L., Van Der Werff, E., & Ünal, A. B. (2019). A meta-analysis of factors related to recycling. Journal of environmental psychology , 64 , 78-97.

Martin, F., Sun, T., & Westine, C. D. (2020). A systematic review of research on online teaching and learning from 2009 to 2018. Computers & education , 159 , 104009.

Mavilidi, M. F., Ruiter, M., Schmidt, M., Okely, A. D., Loyens, S., Chandler, P., & Paas, F. (2018). A narrative review of school-based physical activity for enhancing cognition and learning: The importance of relevancy and integration. Frontiers in psychology , 2079.

Patterson, G. T., Chung, I. W., & Swan, P. W. (2014). Stress management interventions for police officers and recruits: A meta-analysis. Journal of experimental criminology , 10 , 487-513.

Reith, T. P. (2018). Burnout in United States healthcare professionals: a narrative review. Cureus , 10 (12).

Ritchie, S. J., & Tucker-Drob, E. M. (2018). How much does education improve intelligence? A meta-analysis. Psychological science , 29 (8), 1358-1369.

Roman, S., Sánchez-Siles, L. M., & Siegrist, M. (2017). The importance of food naturalness for consumers: Results of a systematic review. Trends in food science & technology , 67 , 44-57.

Sáiz-Vazquez, O., Puente-Martínez, A., Ubillos-Landa, S., Pacheco-Bonrostro, J., & Santabárbara, J. (2020). Cholesterol and Alzheimer’s disease risk: a meta-meta-analysis. Brain sciences, 10(6), 386.

Vermeir, P., Vandijck, D., Degroote, S., Peleman, R., Verhaeghe, R., Mortier, E., … & Vogelaers, D. (2015). Communication in healthcare: a narrative review of the literature and practical recommendations. International journal of clinical practice , 69 (11), 1257-1267.

Wisniewski, B., Zierer, K., & Hattie, J. (2020). The power of feedback revisited: A meta-analysis of educational feedback research. Frontiers in Psychology , 10 , 3087.

Yli-Huumo, J., Ko, D., Choi, S., Park, S., & Smolander, K. (2016). Where is current research on blockchain technology?—a systematic review. PloS one , 11 (10), e0163477.

Zestcott, C. A., Blair, I. V., & Stone, J. (2016). Examining the presence, consequences, and reduction of implicit bias in health care: a narrative review. Group Processes & Intergroup Relations , 19 (4), 528-542

Chris Drew (PhD)

Dr. Chris Drew is the founder of the Helpful Professor. He holds a PhD in education and has published over 20 articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education. [Image Descriptor: Photo of Chris]

• Chris Drew (PhD) https://helpfulprofessor.com/author/chris-drew-phd/ 15 Self-Actualization Examples (Maslow's Hierarchy)
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Training videos   |   Faqs

Literature Review Examples and Writing Tips

Abstract | Introduction | Literature Review | Research question | Materials & Methods | Results | Discussion | Conclusion

In this blog, you will learn how to write the literature review section of a research paper. We will go through many literature review examples and understand different ways to present past literature in your paper.

1. What is the purpose of a literature review?

A literature review is a summary of previous research on your chosen topic. The purpose of the literature review is to let your audience know what others have done in your line of research. The literature review is not about providing a shopping list of past papers. You should structure your literature review so that it flows logically, and provides just the right amount of information to your readers.

2. What should be the length of the literature review?

The length of the literature review section varies from discipline to discipline. Typically, in a standard research paper, the literature review occupies 1 or 2 paragraphs. However, if you are dealing with a topic that requires a strong theoretical foundation, then a significantly longer literature review might be required.

3. How should you structure your literature review?

Generally, in your literature review, you can talk about the following things.

Broad overview or summary It is a good idea to start your literature review with a broad summary of previous research on the topic.

Seminal or pioneering works Here, you can talk about historical papers and famous people who kick-started research in your field.

Specific works Here, you can cite prominent papers that are relevant to your specific study.

Most recent works Then, you can talk about the most recent papers published in your field in the last 2-3 years, that reflect the newest discoveries and theories.

Controversial studies Then, you can talk about controversial literature related to your topic. Here, you can talk about studies that led to conflicts and debates among researchers in your field.

Research gap Then, you have to establish the research gap. You must highlight the drawbacks of previous works, and clearly explain what is missing from the literature.

4. Literature Review Examples

Let’s look at some examples of literature reviews. We will be looking at examples from different subjects and of different formats.

4.1 Example #1 (Social sciences research paper)

Typically in a literature review, you start with broad issues, and then you narrow it down to specific issues. Then, you keep narrowing it down until you reach the articles that are most relevant to your research question.

This literature review example is from a social sciences research paper. The authors have started broadly by saying that the research on mental health is quite varied, and it ranges from medication to therapy. Then, they narrow down the topic to the impact of social factors on depression, and cite a few papers. Then, they further narrow it down to the role of corporate in providing mental health support for their employees. Now, this directly relates to their research problem.

Extensive academic research addresses the topic of mental health in a wide range of contexts, from medication [1-3] to therapy [4-6]. In recent years, research has only begun to examine the impact of social factors on depression [7-8]. Even more recently, marketing research has begun to examine the role of corporate responsibility in promoting mental health support for employees [9-10]. In fact, in the only two such studies that have been conducted to date on this issue, inconsistent findings have been reported. Obviously, more studies are needed. _  Broad summary  _  Narrowing down  _  Further narrowing down  _  Research gap

Then, they explain the research gap. They are saying that there aren’t many previous studies on the topic. In fact, there are only two studies that have been conducted on this topic so far, and the results of those studies are inconsistent.

As you can see the review flows very well. It goes from broad to specific, and nicely finishes off with the research gap.

4.2 Example #2 (Physics research paper)

One of the important qualities of a good literature review is sequentially explaining the events that led up to the current situation.

Here is a literature review example from a physics research paper about atomic theory. In this example, the authors have summarized almost 1000 years of research work in three to four lines. The authors have chronologically provided major theories presented by prominent authors over time. 

In the first approach proposed by Democritus (400BC), a Greek philosopher, suggested that matter is made up of small particles called atoms [1]. The method was further extended by Dalton (1808), who proposed the atomic theory, known as Dalton’s Atomic Theory [2]. Niels Bohr (1913) proposed an alternative suggestion; that the electrons of an atom revolve around a centrally placed nucleus [3]. In more recent work, physicists have successfully created a “giant atom”, these atoms are created at very cold temperatures and are held together by a weak bond [4]. _  First major work  _  Second major work  _  Third major work  _  Most recent work

They start with the first approach presented by Democritus in 400 BC. Then they talk about Dalton’s and Bohr’s theories published in the 18 th and 19 th centuries respectively. Finally, they talk about the most recent work in the field.

Pay attention to the use of phrases such as ‘In the first approach’, ‘was further extended by’, ‘proposed an alternative suggestion’, ‘in recent work’. These phrases are used to connect the events together and make the text flow better. This passage is a very good example that demonstrates how to logically structure your literature review.

4.3 Example #3 (Business research paper)

When you are dealing with large amounts of literature, it is a good idea to group them by ideas before presenting them in your literature review.

Here is a literature review example from a business paper that deals with the consumer behavior of the older population. The author starts with a broad statement stating that there is a lot of literature on the topic of consumer behavior.  Then, the author has grouped articles by ideas, and then presented them in the text. As you can see that almost 20 references are cited in the first two lines.

There exists a vast amount of literature on the topic of consumer behaviour [1-5]. Existing literature on the consumer decision-making process generally explores: Personal factors [6-8], Age factors [9-11], Psychological factors [12-15] and Situational factors [16-20]. There are very limited published previous research findings related to shopping behaviours of older population. This study, to the best of our knowledge, represents the first attempt to fill the void in the literature. _  Broad summary  _  Grouping works by ideas  _  Research gap  _  Novelty of the work

Then, the author establishes the research gap and explains what is unique about their study. They are saying that there are plenty of studies about general consumer behaviour, however, there are very limited studies that specifically deal with the consumer behaviour of the older population. And their study represents the first attempt to investigate this issue.

You can follow this format of literature review when you are short of space but have to include a lot of references. 

4.4 Example #4 (Medical research paper)

Here is an example of a literature review from a medical paper. Here, the authors talk about a controversial and debated topic in literature. The authors say that the evidence linking cycling and male fertility is somewhat mixed. Some studies say that cycling improves fertility since it is good exercise. Whereas other studies say that it is bad because it actually damages the prostate.

Most studies examining the mechanisms linking cycling to male infertility have had conflicting results and is a heavily debated topic [1-2]. Until last decade, there was a general consensus among researchers that cycling improves male fertility [3-9]. The results of the recent large scale multicenter study by Elan et al [10], in contrast to previous studies, showed cycling weakening the prostate tissue causing infertility among males. Due to lack of clear evidence, the link between cycling and male infertility remains unclear. _  Debated topic  _  Mixed/controversial studies  _  Research gap

The authors say that there is a lack of consensus among researchers about this. And we are still not sure which claim is correct, so there is a research gap here.  As you can see, the authors have made their case for further research very elegantly by providing evidence that supports both sides of the argument.

4.5 Example #5 (Health sciences research paper)

Here is another format of literature review that you can follow in your paper. You can talk about a few studies with similar themes or theories at a time. Then you stop and provide your opinion on the studies. You can either summarise the findings or point out the drawbacks of the studies. Then you move on to the next set of studies and do exactly the same.

The simplest approach to deal with weight gain is cutting down food intake [1-3]. This type of diet is hard to maintain, and individuals might be missing out on essential nutrients. An alternative solution is using an intragastric balloon [4-6]. However, this method is expensive and has some life-threatening symptoms and complications. Another solution is to follow a rigorous exercise routine [7-10]. This can increase the risk of injuries. Because of these limitations, there has been significant interest in finding the right treatment for obesity. _  Method 1  _  Critique 1  _  Method 2  _  Critique 2 _  Method 3  _  Critique 3  _  Research gap

Here is a literature review example from health sciences paper, this review is about methods to reduce weight. We start by talking about the papers that deal with fasting techniques. Then, we explain the drawbacks of fasting. Then, we move on to papers that deal with surgery as an option. Then we explain the drawbacks of surgery. Then, we move on to papers that propose exercise as a means to tackle weight gain. Then, we explain the drawbacks of exercise. And then finally, we are stating the research gap.

The literature review flows very well, and the author tells a nice story by logically presenting various techniques and critiquing them at the same time.

5. Frequently Asked Questions

The literature review typically appears after the introduction paragraph of your research paper.

You may have to use multiple tenses in your literature review depending on what you are saying. The present tense is generally used in statements to introduce the literature review. And, the past tense is typically used when you are talking about specific papers.

You should start your literature review with a general summary of previous research on the topic. And then, you should move to specific studies that directly relates to your research work.

One of the best ways to shorten your literature review is by citing review papers. A review paper is a  collection of all relevant literature on a topic. It is common practice to point your readers to review papers for further information in your literature review.

(1) All the papers you cited in the literature review should appear in the bibliography; (2) You must present previous literature that both support and contradict your hypothesis or idea in an unbiased manner; (3) The literature review should flow logically; and (4) You must use constructive and diplomatic language when critizing other’s work in your literature review.

Try to use constructive and diplomatic language in your literature review. Pay specific attention to your language when you are criticizing other researchers in your field.

Look at the following examples. Here, we are pointing out the drawback of previous studies. Look at the first statement, it is quite blunt and we are very critical of previous works. Now look at the second statement, we are giving some credit to the previous authors and appreciating their efforts. And then we are making our claim that there is no solution to the problem.

None of the previous works [1-4] offer a good solution. Very blunt and too critical

Despite the success of previous works [1-4] in certain aspects, the problem is still unsolved. Constructive and diplomatic

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• Common errors

Poor writing in a literature review is often the result of failing to integrate arguments into the review. Many people make the mistake of simply summarising their readings. Avoid using words like 'are reported' . These types of words often lead to descriptive writing.

Look at the following example of poor writing. It illustrates a "He said..." "She said..." pattern which lacks analysis.

During the past decade, many researchers have shown interest in motivation. Their findings are reported here. Smith (2009) developed a model investigation conducted on (the next paragraph describes Smith's model) ... Jones 2010 asserts that... (the following paragraph says what Jones asserted) ... Hoey (2008) makes a clear distinction between... (the following paragraph states what Hoey says)

Good writing in a literature review

The following information is an example of good writing in a literature review because:

• it integrates the research of various authors
• it shows similarities and differences of ideas
• it shows wide reading
• it shows analysis and critical evaluation of what the student has read.

Example - analysis of a paragraph

This paper brings together work in two areas of motivation. According to Robbins et al. (1998) the early theories of motivation were concerned with need satisfaction. Current thinking however, does not discount these theories, but simply builds upon them, to include a self concept. Leonard, Beauvais and Scholl (1999) argue that there are three elements to self-perception. They propose that... These three elements can be seen as a further development of Eunson's original concept of 'money as a motivator'.

Shows the ability to connect the two authors' ideas Demonstrates the student's voice Shows further reading Deeper development of analysis

• 'Connect': shows the ability to connect the two authors' ideas
• 'Student': demonstrates the student's voice
• 'Show': shows further reading
• 'Analysis': deeper development of analysis

This paper [Connect: brings together work] in two areas of motivation. According to Robbins et al. (1998) the early theories of motivation were concerned with need satisfaction. [Student: Current thinking however, does not discount these theories, but simply builds upon them, to include a self concept.] [Show: Leonard, Beauvais and Scholl (1999) argue that] there are three elements to self-perception. They propose that... These three elements can be seen as a [Analysis: further development] of Eunson's original concept of 'money as a motivator'.

Writing checklist

Use the following criteria as guidelines for your literature review.

Traps to avoid in the literature review

• Don't try to read everything, be selective.
• Reading but not writing.
• Not keeping bibliographical information.
• Incomplete referencing (paraphrases, summaries and direct quotes).

What makes a good literature review?

• The selection of literature chosen for review.
• The critique of the literature.
• The interpretation of the literature.

Selection of literature

• Have you read widely?
• Is the purpose of the review clearly identified?
• Does your writing include clear definitions and identify the limits of the research?
• Does the review focus on the most recent developments/research for that topic?
• Does the review make use of the primary sources?

Criticism of the literature

• Is there a logical flow to your writing?
• Is the structure of your review clearly stated?
• Have you demonstrated that you have read widely as well as focused on your specific topic of research?
• Have you focused on current/most relevant issues?

Interpretation

• Have you interpreted/evaluated what you have read?
• Is there an obvious gap in the research/literature?
• Have you used the literature to create your own interpretation of the research?

Key assessment criteria

• What the student has read.
• How the student has organised the review/writing of this.
• How the student has interpreted and evaluated this.
• Read and research

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A Bad Example of a Literature Review

REVIEWING THE LITERATURE

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Review of Related Literature (RRL)

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The Review of Related Literature (RRL) is a crucial section in research that examines existing studies and publications related to a specific topic. It summarizes and synthesizes previous findings, identifies gaps, and provides context for the current research. RRL ensures the research is grounded in established knowledge, guiding the direction and focus of new studies.

What Is Review of Related Literature (RRL)?

The Review of Related Literature (RRL) is a detailed analysis of existing research relevant to a specific topic. It evaluates, synthesizes, and summarizes previous studies to identify trends, gaps, and conflicts in the literature. RRL provides a foundation for new research, ensuring it builds on established knowledge and addresses existing gaps.

Format of Review of Related Literature (RRL)

The Review of Related Literature (RRL) is a critical part of any research paper or thesis . It provides an overview of existing research on your topic and helps to establish the context for your study. Here is a typical format for an RRL:

1. Introduction

• Purpose : Explain the purpose of the review and its importance to your research.
• Scope : Define the scope of the literature reviewed, including the time frame, types of sources, and key themes.

2. Theoretical Framework

• Concepts and Theories : Present the main theories and concepts that underpin your research.
• Relevance : Explain how these theories relate to your study.

3. Review of Empirical Studies

• Sub-theme 1 : Summarize key studies, including methodologies, findings, and conclusions.
• Sub-theme 2 : Continue summarizing studies, focusing on different aspects or variables.
• Sub-theme 3 : Include any additional relevant studies.

4. Methodological Review

• Approaches : Discuss the various methodologies used in the reviewed studies.
• Strengths and Weaknesses : Highlight the strengths and weaknesses of these methodologies.
• Gaps : Identify gaps in the existing research that your study aims to address.

5. Synthesis and Critique

• Integration : Integrate findings from the reviewed studies to show the current state of knowledge.
• Critique : Critically evaluate the literature, discussing inconsistencies, limitations, and areas for further research.

6. Conclusion

• Summary : Summarize the main findings from the literature review.
• Research Gap : Clearly state the research gap your study will address.
• Contribution : Explain how your study will contribute to the existing body of knowledge.

7. References

• Citation Style : List all the sources cited in your literature review in the appropriate citation style (e.g., APA, MLA, Chicago).

Review of Related Literature (RRL) 1. Introduction This review examines research on social media’s impact on mental health, focusing on anxiety and depression across various demographics over the past ten years. 2. Theoretical Framework Anchored in Social Comparison Theory and Uses and Gratifications Theory, this review explores how individuals’ social media interactions affect their mental health. 3. Review of Empirical Studies Adolescents’ Mental Health Instagram & Body Image : Smith & Johnson (2017) found Instagram use linked to body image issues and lower self-esteem among 500 high school students. Facebook & Anxiety : Brown & Green (2016) showed Facebook use correlated with higher anxiety and depressive symptoms in a longitudinal study of 300 students. Young Adults’ Mental Health Twitter & Stress : Davis & Lee (2018) reported higher stress levels among heavy Twitter users in a survey of 400 university students. LinkedIn & Self-Esteem : Miller & White (2019) found LinkedIn use positively influenced professional self-esteem in 200 young professionals. Adult Mental Health General Social Media Use : Thompson & Evans (2020) found moderate social media use associated with better mental health outcomes, while excessive use correlated with higher anxiety and depression in 1,000 adults. 4. Methodological Review Studies used cross-sectional surveys, longitudinal designs, and mixed methods. Cross-sectional surveys provided large data sets but couldn’t infer causation. Longitudinal studies offered insights into long-term effects but were resource-intensive. Mixed methods enriched data through qualitative insights but required careful integration. 5. Synthesis and Critique The literature shows a complex relationship between social media and mental health, with platform-specific and demographic-specific effects. However, reliance on self-reported data introduces bias, and many cross-sectional studies limit causal inference. More longitudinal and experimental research is needed. 6. Conclusion Current research offers insights into social media’s mental health impact but leaves gaps, particularly regarding long-term effects and causation. This study aims to address these gaps through comprehensive longitudinal analysis. 7. References Brown, A., & Green, K. (2016). Facebook Use and Anxiety Among High School Students . Psychology in the Schools, 53(3), 257-264. Davis, R., & Lee, S. (2018). Twitter and Psychological Stress: A Study of University Students . Journal of College Student Development, 59(2), 120-135. Miller, P., & White, H. (2019). LinkedIn and Its Effect on Professional Self-Esteem . Journal of Applied Psychology, 104(1), 78-90. Smith, J., & Johnson, L. (2017). The Impact of Instagram on Teen Body Image . Journal of Adolescent Health, 60(5), 555-560. Thompson, M., & Evans, D. (2020). The Relationship Between Social Media Use and Mental Health in Adults . Cyberpsychology, Behavior, and Social Networking, 23(4), 201-208.

Review of Related Literature (RRL) Examples

Review of related literature in research, review of related literature in research paper, review of related literature qualitative research.

Review of Related Literature Quantitative Research

More Review of Related Literature (RRL) Examples

• Impact of E-learning on Student Performance
• Effectiveness of Mindfulness in Workplace
• Green Building and Energy Efficiency
• Impact of Technology on Healthcare Delivery
• Effects of Nutrition on Cognitive Development in Children
• Impact of Employee Training Programs on Productivity
• Effects of Climate Change on Biodiversity
• Impact of Parental Involvement on Student Achievement
• Effects of Mobile Learning on Student Engagement
• Effects of Urban Green Spaces on Mental Health

Purpose of the Review of Related Literature (RRL)

The Review of Related Literature (RRL) serves several critical purposes in research:

• Establishing Context : It situates your research within the broader field, showing how your study relates to existing work.
• Identifying Gaps : It highlights gaps, inconsistencies, and areas needing further exploration in current knowledge, providing a clear rationale for your study.
• Avoiding Duplication : By reviewing what has already been done, it helps ensure your research is original and not a repetition of existing studies.
• Building on Existing Knowledge : It allows you to build on the findings of previous research, using established theories and methodologies to inform your work.
• Theoretical Foundation : It provides a theoretical basis for your research, grounding it in existing concepts and theories.
• Methodological Insights : It offers insights into the methods and approaches used in similar studies, helping you choose the most appropriate methods for your research.
• Establishing Credibility : It demonstrates your familiarity with the field, showing that you are well-informed and have a solid foundation for your research.
• Supporting Arguments : It provides evidence and support for your research questions, hypotheses, and objectives, strengthening the overall argument of your study.

How to Write Review of Related Literature (RRL)

Writing a Review of Related Literature (RRL) involves several key steps. Here’s a step-by-step guide:

1. Define the Scope and Objectives

• Determine the Scope : Decide on the breadth of the literature you will review, including specific themes, time frame, and types of sources.
• Set Objectives : Clearly define the purpose of the review. What do you aim to achieve? Identify gaps, establish context, or build on existing knowledge.

2. Search for Relevant Literature

• Identify Keywords : Use keywords and phrases related to your research topic.
• Use Databases : Search academic databases like Google Scholar, PubMed, JSTOR, etc., for relevant articles, books, and papers.
• Select Sources : Choose sources that are credible, recent, and relevant to your research.

3. Evaluate and Select the Literature

• Read Abstracts and Summaries : Quickly determine the relevance of each source.
• Assess Quality : Consider the methodology, credibility of the authors, and publication source.
• Select Key Studies : Choose studies that are most relevant to your research questions and objectives.

4. Organize the Literature

• Thematic Organization : Group studies by themes or topics.
• Chronological Organization : Arrange studies in the order they were published to show the development of ideas over time.
• Methodological Organization : Categorize studies by the methods they used.

5. Write the Review

• State the purpose and scope of the review.
• Explain the importance of the topic.
• Theoretical Framework : Present and discuss the main theories and concepts.
• Summarize key studies, including their methodologies, findings, and conclusions.
• Organize by themes or other chosen organizational methods.
• Methodological Review : Discuss the various methodologies used, highlighting their strengths and weaknesses.
• Synthesis and Critique : Integrate findings, critically evaluate the literature, and identify gaps or inconsistencies.
• Summarize the main findings from the literature review.
• Highlight the research gaps your study will address.
• State how your research will contribute to the existing knowledge.

6. Cite the Sources

• Use Appropriate Citation Style : Follow the required citation style (e.g., APA, MLA, Chicago).
• List References : Provide a complete list of all sources cited in your review.

What is an RRL?

An RRL summarizes and synthesizes existing research on a specific topic to identify gaps and guide future studies.

Why is RRL important?

It provides context, highlights gaps, and ensures new research builds on existing knowledge.

How do you write an RRL?

Organize by themes, summarize studies, evaluate methodologies, identify gaps, and conclude with relevance to current research.

What sources are used in RRL?

Peer-reviewed journals, books, conference papers, and credible online resources.

How long should an RRL be?

Length varies; typically 10-20% of the total research paper.

What are common RRL mistakes?

Lack of organization, insufficient synthesis, over-reliance on outdated sources, and failure to identify gaps.

Can an RRL include non-scholarly sources?

Primarily scholarly, but reputable non-scholarly sources can be included for context.

What is the difference between RRL and bibliography?

RRL synthesizes and analyzes the literature, while a bibliography lists sources.

How often should an RRL be updated?

Regularly, especially when new relevant research is published.

Can an RRL influence research direction?

Yes, it identifies gaps and trends that shape the focus and methodology of new research.

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Why Google’s AI Overviews gets things wrong

Google’s new AI search feature is a mess. So why is it telling us to eat rocks and gluey pizza, and can it be fixed?

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MIT Technology Review Explains: Let our writers untangle the complex, messy world of technology to help you understand what's coming next. You can read more here.

When Google announced it was rolling out its artificial-intelligence-powered search feature earlier this month, the company promised that “Google will do the googling for you.” The new feature, called AI Overviews, provides brief, AI-generated summaries highlighting key information and links on top of search results.

Unfortunately, AI systems are inherently unreliable. Within days of AI Overviews’ release in the US, users were sharing examples of responses that were strange at best. It suggested that users add glue to pizza or eat at least one small rock a day , and that former US president Andrew Johnson earned university degrees between 1947 and 2012, despite dying in 1875. 

On Thursday, Liz Reid, head of Google Search, announced that the company has been making technical improvements to the system to make it less likely to generate incorrect answers, including better detection mechanisms for nonsensical queries. It is also limiting the inclusion of satirical, humorous, and user-generated content in responses, since such material could result in misleading advice.

But why is AI Overviews returning unreliable, potentially dangerous information? And what, if anything, can be done to fix it?

How does AI Overviews work?

In order to understand why AI-powered search engines get things wrong, we need to look at how they’ve been optimized to work. We know that AI Overviews uses a new generative AI model in Gemini, Google’s family of large language models (LLMs), that’s been customized for Google Search. That model has been integrated with Google’s core web ranking systems and designed to pull out relevant results from its index of websites.

Most LLMs simply predict the next word (or token) in a sequence, which makes them appear fluent but also leaves them prone to making things up. They have no ground truth to rely on, but instead choose each word purely on the basis of a statistical calculation. That leads to hallucinations. It’s likely that the Gemini model in AI Overviews gets around this by using an AI technique called retrieval-augmented generation (RAG), which allows an LLM to check specific sources outside of the data it’s been trained on, such as certain web pages, says Chirag Shah, a professor at the University of Washington who specializes in online search.

Once a user enters a query, it’s checked against the documents that make up the system’s information sources, and a response is generated. Because the system is able to match the original query to specific parts of web pages, it’s able to cite where it drew its answer from—something normal LLMs cannot do.

One major upside of RAG is that the responses it generates to a user’s queries should be more up to date, more factually accurate, and more relevant than those from a typical model that just generates an answer based on its training data. The technique is often used to try to prevent LLMs from hallucinating. (A Google spokesperson would not confirm whether AI Overviews uses RAG.)

So why does it return bad answers?

But RAG is far from foolproof. In order for an LLM using RAG to come up with a good answer, it has to both retrieve the information correctly and generate the response correctly. A bad answer results when one or both parts of the process fail.

In the case of AI Overviews’ recommendation of a pizza recipe that contains glue—drawing from a joke post on Reddit—it’s likely that the post appeared relevant to the user’s original query about cheese not sticking to pizza, but something went wrong in the retrieval process, says Shah. “Just because it’s relevant doesn’t mean it’s right, and the generation part of the process doesn’t question that,” he says.

Similarly, if a RAG system comes across conflicting information, like a policy handbook and an updated version of the same handbook, it’s unable to work out which version to draw its response from. Instead, it may combine information from both to create a potentially misleading answer. 

“The large language model generates fluent language based on the provided sources, but fluent language is not the same as correct information,” says Suzan Verberne, a professor at Leiden University who specializes in natural-language processing.

The more specific a topic is, the higher the chance of misinformation in a large language model’s output, she says, adding: “This is a problem in the medical domain, but also education and science.”

According to the Google spokesperson, in many cases when AI Overviews returns incorrect answers it’s because there’s not a lot of high-quality information available on the web to show for the query—or because the query most closely matches satirical sites or joke posts.

The spokesperson says the vast majority of AI Overviews provide high-quality information and that many of the examples of bad answers were in response to uncommon queries, adding that AI Overviews containing potentially harmful, obscene, or otherwise unacceptable content came up in response to less than one in every 7 million unique queries. Google is continuing to remove AI Overviews on certain queries in accordance with its content policies. 

It’s not just about bad training data

Although the pizza glue blunder is a good example of a case where AI Overviews pointed to an unreliable source, the system can also generate misinformation from factually correct sources. Melanie Mitchell, an artificial-intelligence researcher at the Santa Fe Institute in New Mexico, googled “How many Muslim presidents has the US had?’” AI Overviews responded: “The United States has had one Muslim president, Barack Hussein Obama.” 

While Barack Obama is not Muslim, making AI Overviews’ response wrong, it drew its information from a chapter in an academic book titled Barack Hussein Obama: America’s First Muslim President? So not only did the AI system miss the entire point of the essay, it interpreted it in the exact opposite of the intended way, says Mitchell. “There’s a few problems here for the AI; one is finding a good source that’s not a joke, but another is interpreting what the source is saying correctly,” she adds. “This is something that AI systems have trouble doing, and it’s important to note that even when it does get a good source, it can still make errors.”

Can the problem be fixed?

Ultimately, we know that AI systems are unreliable, and so long as they are using probability to generate text word by word, hallucination is always going to be a risk. And while AI Overviews is likely to improve as Google tweaks it behind the scenes, we can never be certain it’ll be 100% accurate. Google has said that it’s adding triggering restrictions for queries where AI Overviews were not proving to be especially helpful and has added additional “triggering refinements” for queries related to health. The company could add a step to the information retrieval process designed to flag a risky query and have the system refuse to generate an answer in these instances, says Verberne. Google doesn’t aim to show AI Overviews for explicit or dangerous topics, or for queries that indicate a vulnerable situation, the company spokesperson says.

Techniques like reinforcement learning from human feedback, which incorporates such feedback into an LLM’s training, can also help improve the quality of its answers. 

Similarly, LLMs could be trained specifically for the task of identifying when a question cannot be answered, and it could also be useful to instruct them to carefully assess the quality of a retrieved document before generating an answer, Verbene says: “Proper instruction helps a lot!” 

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The jury convicted Trump. Here’s what could happen next.

A guilty verdict for Trump in the New York trial means a mix of routine court processing and extraordinary logistical considerations, legal experts say.

On Thursday afternoon, after more than a day of deliberations, a jury in Manhattan convicted Donald Trump on all 34 counts of falsifying business records related to a 2016 hush money payment.

During the seven-week trial, Trump complained of the indignities of a cold, uncomfortable courtroom. The former president and presumptive 2024 Republican nominee may now face other conditions he may consider insulting, including a required inmate review by the New York City Department of Probation.

The probation office on the 10th floor of the Manhattan Criminal Courthouse prepares presentencing reports for judges. There, Trump would be interviewed about his personal history, his mental health and the circumstances that led to his conviction.

Lawyers say the process is humbling.

“If you think the courtroom is dingy, just wait until you go to the probation office,” said Daniel Horwitz, a white-collar criminal defense attorney in New York and former prosecutor in the Manhattan district attorney’s office.

Trump guilty verdict

Former prosecutors sketched out a mix of likely experiences for Trump, who is now a felon. Trump was convicted of charges relating to $130,000 in payments made to adult-film actress Stormy Daniels before the 2016 presidential election to keep her quiet about a sexual encounter she said they had.

The routine processing of felons into the New York criminal justice system would include the timeline of a potential appeal. But with Trump, there would also be extraordinary considerations — such as how the Secret Service would protect the former president if he were sent to prison and whether he would be allowed to travel to campaign events if sentenced to home confinement.

Legal experts said incarceration appears unlikely for Trump, 77, who has no criminal record.

The Class E felony charges are punishable by 16 months to four years in prison. Among the key issues to be determined would be whether Trump faces some form of incarceration, either in a government facility or a private location, or a less-restrictive experience through probation.

New York Mayor Eric Adams said this month that the city’s Rikers Island jail complex and Department of Corrections were prepared if Trump were ordered to serve time.

His conviction does not disqualify him from running for office or serving as president if elected, constitutional experts said.

During the trial, which began April 15, prosecutors with Manhattan District Attorney Alvin Bragg’s office said Trump falsely recorded the payments involving Daniels as legal expenses and alleged they were improper campaign expenditures. Defense attorneys said Trump, who pleaded not guilty, made personal payments to protect his family from an embarrassing disclosure.

The jury, which heard closing arguments Tuesday, unanimously agreed to convict on all counts after hours of deliberations spread over two days.

Trump’s punishment is now up to New York Supreme Court Justice Juan Merchan , who will receive input from the prosecution and defense in the presentencing report. Though jail or prison are unlikely , the former prosecutors said, alternatives such as probation or home confinement would create logistical challenges and potential political concerns.

If he is sentenced to probation, for example, Trump would be required to clear any out-of-state travel — such as to campaign rallies and fundraisers — with a probation officer. If Trump were to serve home confinement at his Mar-a-Lago resort in Palm Beach, Fla., New York authorities would probably have to work with counterparts in Florida to accommodate him, the experts said.

Such arrangements are not uncommon for felons, experts said, but probation officers must approve the details.

“If you have a probation officer, you are not supposed to travel without permission. Your home is subject to random search because you don’t have a Fourth Amendment right to your home being private. You can get drug-tested, potentially. Travel outside the country is difficult,” said Matthew Galluzzo, another former prosecutor in the Manhattan district attorney’s office.

“That would be super awkward for someone on the campaign trail, but not impossible,” Galluzzo said. “If he had to go to a debate against Biden, he probably could go, but you’re supposed to make that request far in advance.”

Trump and President Biden have agreed to two debates . The first is scheduled for June 27 in Atlanta, before Trump’s sentencing, which Merchan scheduled for July 11. A second debate is planned for Sept. 10 at a yet-undisclosed location.

The probation office will put together a presentencing report for Merchan. As part of that process, Trump must be interviewed by a probation officer, who will produce a biography of him of about five or six pages, legal experts said. Such documents are confidential, intended only for the judge and the lawyers.

Trump has called his prosecution politically motivated and denigrated Merchan, Bragg and others , leading the judge to fine him 10 times for a total of $10,000 during the trial for violating a partial gag order . How Trump would react to questions from a probation officer about the case could get him into more hot water with the court. Legal experts said his attorneys probably would advise him not to discuss the case.

Convicts are “expected to tell the truth. If they are convicted and then say, ‘No, it’s a lie, it didn’t happen,’ that will go back to the judge. And that’s not good,” said defense lawyer Jeremy Saland, who also served as a Manhattan prosecutor.

The prosecution and Trump’s legal team also are expected to submit recommendations about the sentencing.

Because he was charged with nonviolent crimes, Trump is unlikely to be detained in prison as he awaits sentencing, said the experts, who added that it is also unlikely that Merchan would impose bail as a condition for his release.

Trump’s team has 30 days to file notice of appeal and six months to file the full appeal.

A key question is whether the court would agree to stay Trump’s sentence pending an appeal, a process that is likely to last well beyond the Nov. 5 presidential election. Former prosecutors suggested such a scenario is plausible given that any punishment of Trump could be short enough in duration that the sentence would be fully carried out before a legal appeal is litigated.

The legal experts said Merchan could grant Trump a conditional discharge tied to the requirement that he not commit another legal offense. Merchan also could impose a financial penalty or require Trump to do community service or undergo counseling, some legal experts said.

If the judge were to impose a more onerous penalty, such as home confinement, Trump could still find ways to continue campaigning, even if he were not on the road.

“He could be confined but go to Mar-a-Lago and hold a news conference every day, be on TV, hold rallies remotely,” Horwitz said. “There’s a lot he can do as a candidate while under home confinement.”

Trump New York hush money case

Donald Trump is the first former president convicted of a crime .

Can Trump still run for president? Yes. He is eligible to campaign and serve as president if elected, but he won’t be able to pardon himself . Here’s everything to know about next steps , what this means for his candidacy and the other outstanding trials he faces .

What happens next? Trump’s sentencing is scheduled for July 11. He faces up to four years in prison, but legal experts say incarceration appears unlikely. Trump has 30 days to file notice of an appeal of the verdict and six months to file the full appeal.

Reaction to the verdict: Trump continued to maintain his innocence , railing against what he called a “rigged, disgraceful trial” and emphasizing voters would deliver the real verdict on Election Day.

The charges: Trump was found guilty on 34 felony counts of falsifying business records . Falsifying business records is a felony in New York when there is an “intent to defraud” that includes an intent to “commit another crime or to aid or conceal” another crime.