Doing a literature review is an important part of any research project or exegesis. It requires you to be able to search the literature effectively and, for some review types, comprehensively.
It is important to choose a review type that matches the aim and scope of your research.
Depending on the type of review you undertake, the following elements will differ:
See the links below to help get you started.
Some discipline areas have established guidelines and reporting standards you should follow when undertaking certain types of reviews. These ensure that you follow best practices.
If you are doing a systematic review or scoping review, see the Library Guides below:
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This table will help you to choose the most suitable review methodology for your purpose.
| Review type | What is it? | Search strategy | Selected guidance |
| Systematic review | ‘A systematic review attempts to collate all the empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question. It uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made’ - Lasserson et al. (2023), Cochrane Handbook, Ch. 1 |
Searching is systematic, comprehensive*, transparent and reproducible. A combination of database searching and other approaches is recommended. * Iterative and sampling approaches may be used for some forms of qualitative synthesis – see Cochrane-Campbell Handbook for Qualitative Evidence Synthesis |
There are many guides to the conduct of systematic reviews, for health and other disciplinary areas. See Guidelines and standards for key links. The Cochrane Handbook is the core guide for health and many others are based on this. |
| Scoping review | Aims to provide an overview or map of the available evidence, focusing on a particular topic, field, concept, or issue. Conducted according to similar rigorous and transparent methods as systematic reviews, but typically answers broad questions and generally does not require critical appraisal. | Searching is systematic, comprehensive, transparent and reproducible. A combination of database searching and other approaches is recommended. | JBI Manual for Evidence Synthesis - Chapter 10: Scoping Reviews (Peters et al., 2020) |
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Literature review |
Literature reviews examine existing knowledge on a specified topic. They can provide an historical overview of a field of research, show emerging trends, identify knowledge gaps, and/or contextualise a research project within the broader scholarly conversation. | Searching approach varies depending on review purpose, any requirements, resources, etc. | The Sage Research Methods database has a range of resources (books, videos, etc.) that provide guidance for those undertaking literature reviews. |
| Meta-analysis |
‘Meta-analysis is the statistical combination of results from two or more separate studies’ - Deeks et al. (2023), Cochrane Handbook, Ch. 10 A meta-analysis is often conducted as part of a systematic review, but is not a review type – it is a statistical method. |
Meta-analysis may be undertaken from a known set of studies, or studies identified through a comprehensive search conducted as part of a systematic review. | Cochrane Handbook for Systematic Reviews of Interventions – Chapter 10: Analysing data and undertaking meta-analyses (Deeks et al., 2023) |
| Systematic literature review | Systematic reviews undertaken in areas outside of health are referred to as systematic literature reviews in some discipline areas, such as software engineering. These reviews take traditional systematic reviews guidelines (e.g. from health sciences) and amend to suit their discipline area, reflecting differences in elements such as study design and sources of evidence. | Searches aim to be as comprehensive as possible, to search a range of sources, and to report strategies in full. Search strategies are often conducted in databases that do not have consistently indexed subject headings and thus rely on keywords alone. Other search approaches such as citation analysis are often used in additional to traditional database searches. |
Kitchenham, B., Charters, S. (2007). Guidelines for performing systematic literature reviews in software engineering. EBSE Technical Report. Xiao, Y., & Watson, M. (2019). Guidance on Conducting a Systematic Literature Review. Journal of Planning Education and Research, 39(1), 93-112. https://doi.org/10.1177/0739456X17723971 |
| Critical review | A critical review ‘goes beyond mere description of identified articles and includes a degree of analysis and conceptual innovation ... The "critical" component of this type of review is key to its value. ... An effective critical review presents, analyses and synthesizes material from diverse sources.' Grant & Booth (2009, p. 93) |
Search strategies are generally not reported and can often be representative/selective rather than comprehensive. There are a variety of search approaches applied. | Critical reviews do not have a centrally recognised methodology or set of guidelines and can differ between disciplines. Many papers labelled as critical reviews will not refer to or follow any specific guidelines or methodological paper. |
| Integrative review | Primarily used to support evidence based practice in nursing. Synthesises diverse empirical, methodological and/or theoretical literature for a broad, well defined purpose and/or review question/s using a systematic process including establishment of eligibility criteria, a comprehensive literature search, screening, quality appraisal, data analysis, and narrative or thematic synthesis. | Comprehensive, transparently reported and replicable, including both literature databases and other sources/approaches. No specific established reporting guidelines but recommended to follow PRISMA and include a flow diagram. |
Toronto, C. E., & Remington, R. (2020). A step-by-step guide to conducting an integrative review. Springer. https://doi.org/10.1007/978-3-030-37504-1 Whittemore, R., & Knafl, K. (2005). The integrative review: Updated methodology. Journal of Advanced Nursing, 52(5), 546-553. https://doi.org/10.1111/j.1365-2648.2005.03621.x (human resources focus) Torraco, R. J. (2005). Writing integrative literature reviews: Guidelines and examples. Human Resource Development Review, 4(3), 356-367. https://doi.org/10.1177/1534484305278283 |
| Rapid review | 'A rapid review is a type of evidence synthesis that brings together and summarises information from different research studies to produce evidence for people such as the public, healthcare providers, researchers, policy makers, and funders in a systematic, resource efficient manner. This is done by speeding up the ways we plan, do, and/or share the results of conventional structured (systematic) reviews, by simplifying or omitting a variety of methods that should be clearly defined by the authors.' - Garritty et al. (2024), p. 3 |
A limited number of key databases (at least two) is used. Grey literature and supplemental searching may also be valuable depending on the review, but is carefully bounded due to resourcing. Klerings et al. (2023) provide practical guidance on searching for rapid reviews. |
CochraneMethods - Rapid Reviews - Methods Related Publications |
| Umbrella review (aka 'overview of reviews', 'overview', 'review of reviews', 'meta-review') | Umbrella reviews use explicit and systematic methods to search for, identify, extract data from, and analyse the results of multiple reviews (often systematic reviews) on related research questions. These overviews are undertaken where multiple existing reviews on a topic already exist and: a summary would benefit decision-makers; reviews have inconclusive evidence or conflicting conclusions; or you would like to look at new (typically broader) questions than those addressed in individual reviews. | Searching is systematic, comprehensive, transparent, and reproducible. Systematic review study design search filters are often used to help locate relevant evidence syntheses. Grey literature such as reports may be included. May involve searching for additional primary studies. |
JBI Manual for Evidence Synthesis - Chapter 9: Umbrella reviews (Aromataris et al., 2020) |
| Realist review (aka 'realist synthesis') | 'Realist synthesis is an approach to reviewing research evidence on complex social interventions, which provides an explanatory analysis of how and why they work (or don’t work) in particular contexts or settings' - Pawson et al. (2004, p. iv). The main unit of analysis is 'mechanisms of action'. | A purposive sampling approach is taken. Searching is iterative (repeated with refinements), and conducted only until theoretical saturation is reached. Diverse types of evidence from published and grey literature sources may be included. The search for evidence to test programme theories should be recorded and transparently reported. |
Pawson, R., Greenhalgh, T., Harvey, G., & Walshe, K. (2004, August). Realist synthesis: An introduction (ESRC Research Methods Programme Working Paper Series 2/2004). University of Manchester. https://www.betterevaluation.org/sites/default/ The RAMESES Projects website links to extensive resources supporting both conduct and reporting |
Additional resources on review types: