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Systematic reviews: Introduction

An introduction to this guide

This guide provides advice to help researchers undertake the various steps of a systematic review.  Work through the guide by clicking the tabs at the top of the page

What is a systematic review?      

  • A systematic review provides a fully-informed and unbiased answer to a focused research question.  It can be written on any academic topic.  Most systematic reviews address healthcare and medicine, but increasingly, psychology and social policy are covered.  It may include recommendations for professional practice or further research. 
  • It searches for, summarises, analyses and synthesises a full range of evidence (published and unpublished).
  • It accounts for differences in research methods and sample sizes and may give more weight to certain types of study when assessing quality.   
  • Normally, it documents the search process so that other researchers can reproduce the same sets of results.

An overview of the process

  1. Formulate a research question which should be focused and well-defined.  
  2. Write a protocol for your literature searching, screening criteria, data extraction and analysis, synthesis of results and dissemination.  
  3. Search the literature (published and unpublished) on your topic, using the Library's databases. You need to build an effective strategy for searching each database.  
  4. Manage references. You will collect a large number of literature references and need a system for storing and managing these. 
  5. Select studies from the literature you found which are suitable for inclusion in your review. Check for quality and risk of bias in each study. 
  6. Assess the evidence. Extract and analyse the data, interpret and synthesise findings, draw conclusions and make recommendations.
  7. Write your review. Include a detailed report of databases used and your search strategy for each of them.

Differences between systematic reviews and systematic literature reviews

Be careful! You may need to confirm whether you need to undertake a systematic review or just a systematic literature review. Doing a systematic review does involve a literature review but it also involves other processes and normally takes longer to complete. 

Systematic Review
(includes a systematic literature review)

Systematic Literature Review only

May take months or years to produce.

May take weeks or months to produce.

Answers a well-defined and focused research question.

The topic may be broad.

Includes a written protocol (a reasoned plan for the entire review process).

Involves a detailed search strategy.

Searches for all published and unpublished literature on a topic.

Searches extensively for published literature on a topic.

Systematically assesses the quality and potential bias of all available evidence.

Summarises the literature and is less evaluative. 

Synthesises all findings and meta-analyses all data.

 

Records and writes up details of all databases searched, search terms used and numbers of results. 

 

May make recommendations for professional practice or further research.

 

Find out more about the process

The Library has taken out a trial subscription to Cochrane Interactive Learning which provides 10 tutorials (modules) on the complete systematic review process. Each module lasts 1-2 hours and contains an assessment. Once you pass an assessment, you can download a certificate. To use this resource, you must first register:

Once you are registered:

Log in to Cochrane Interactive Learning


An alternative learning option is the following 
freely-available online course from Johns Hopkins University: ‚Äč

Introduction to Systematic Review and Meta-Analysis by John Hopkins University

Other types of review

Rapid reviews: similar to systematic reviews but more likely to be completed within weeks rather than months so the literature search is less thorough. Rigorous assessment of evidence is expected but limited given the timeframe so reviewers must be alert to potential bias. 

Scoping reviews: involve broad research questions and comprehensive literature searches. They may take at least a year to complete, requiring different searches, possible changes in selection criteria and a lot of manual screening of results. The synthesis of findings does not require a formal process. Critical assessment is optional. Use of a protocol is advised.