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Systematic Reviews

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This guide gives an overview of what a systematic review is, with a focus on planning and carrying out a systematic search. We suggest that you work through this guide step-by-step, before seeking additional Library help. It does not cover any advice on assessing studies e.g. meta-analysis or synthesis of findings. If you need any additional information about Systematic Reviews, please look in the 'Further help and support' section.
What is a Systematic Review?
 

Defining Systematic Reviews

Definitions of systematic reviews vary but high quality reviews usually aim to answer a research question by:

  • a clearly stated set of objectives with pre-defined eligibility criteria for studies;
  • an explicit, reproducible methodology;
  • a systematic search that attempts to identify all studies (published and sometimes unpublished) that would meet the eligibility criteria;
  • an assessment of the validity of the findings of the included studies, for example through the assessment of risk of bias; and
  • a systematic presentation, and synthesis, of the characteristics and findings of the included studies.

(Cochrane Handbook Section 1.2.2)

Types of Systematic Reviews

There are different types of Systematic Reviews. These include:

  • Rapid reviews;
  • Reviews of reviews / Overviews / Umbrella reviews;
  • Scoping reviews / systematic maps;
  • Standard systematic reviews.

For more information, on different types of reviews, please click here.

Standard systematic reviews come in many shapes and sizes and vary between subjects.  Complex questions can involve large teams of researchers and can take months to complete. Smaller reviews can involve one or two people (ideally screening of results should be carried out by two people independently).  Resources and time will influence what level of review you can complete.  It is vital that you discuss with your supervisor exactly what they expect you to do.

Conducting a systematic review, although it does involve a series of steps, is not a linear process.  You may need to revisit some of the steps more than once.

Is your review a Systematic Review?
 

Ask yourself the following questions: 

  1. Are you expected to include only published material (excluding conference papers, Randomised Control Trials (RCTs), dissertations, theses)?
  2. Are you being led to search only in a restricted number of databases?
  3. Have you been told to include only a specific number of results?
  4. Have you been advised to limit by date or language to restrict the numbers of results?

If you have answered yes to any of the questions above, it may be that you are doing a systematic literature review rather than a systematic review. If this is the case, then this guide will still be of use to you, but you may not have to follow all the steps in full. Always check with a supervisor and discuss if you are unsure. 

Links to relevant articles and books about Systematic Reviews
 

Bayliss, H.R., Lortie, C.J. and Stewart, G.B. (2015) 'How "good" is half a fish? Communicating outcomes of quantitative syntheses to decision makers', Frontiers in Ecology and the Environment, 13(10): pp. 533-534.

Booth, A. (2001) 'Cochrane or cock-eyed? How should we conduct systematic reviews of qualitative research?' in Qualitative Evidence-based conference: Taking a critical stance, Coventry University.

Cooper, H. Hedges, L.V., & Valentine, J.C. Handbook of research synthesis and meta-analysis (2009) 2nd ed. New York: Russell Sage Foundation

Eden, J., Levit, L., Berg, A., and Morton, S. (eds) (2011) Finding What Works in Health Care: Standards for Systematic Reviews. Washington (DC): National Academies Press.

Hemingway, P. (2009) What is a systematic review? Available from: https://docplayer.net/84335-What-is-a-systematic-review.html [Accessed: 28/02/2024]. 

Higgins, J.P.T., Lasserson, T., Chandler, J., Tovey, D., Thomas, J., Flemyng, E., and Churchill, R. (2022) Methodological Expectations of Cochrane Intervention Reviews. London: Cochrane Community.

Khan, K. (2003) ‘Five steps to conducting a systematic review', Journal of the Royal Society of Medicine, 96, pp. 118-121.

Koricheva, J., Gurevitch, J. & Mengersen, K. (eds.) (2013) Handbook of Meta-Analysis in Ecology and Evolution. Princeton: Princeton University Press.

Meerpohl, J.J. et al. (2012) 'Scientific value of systematic reviews: survey of editors of core clinical journals', PLoS ONE, 7(5): p. e35732. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3341385/pdf/pone.0035732.pdf [Accessed: 09/09/2019].

Petticrew, M & Roberts, H. (2006) Systematic reviews in the social sciences: a practical guide. Malden, MA : Blackwell Pub.

Uman, L.S. (2011) 'Systematic reviews and meta-analyses', Journal of the Canadian Academy of Child and Adolescent Psychiatry, 20(1), pp. 57-59. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3024725/ [Accessed: 09/09/2019].

Whaley, P., Aiassa, E., Beausoleil, C., Beronius, A., Bilotta, G., Boobis, A., de Vries, R., Hanberg, A. Hoffmann, S., Hunt, N., Kwiatkowski, C.F., Lam, J., Lipworth, S., Martin, O., Randall, N., Rhomberg, L., Rooney, A.A., Schunemann, H.J., Wikoff, G., Wolffe, T., and Halsall, C. (2020) Recommendations for the conduct of systematic reviews in toxicology and environmental health research  (COSTER), Environment International, 143, p. 105926.