The Campbell Collaboration
 

What is a systematic review?


The purpose of a systematic review is to sum up the best available research on a specific question. This is done by synthesizing the results of several studies.

A systematic review uses transparent procedures to find, evaluate and synthesize the results of relevant research. Procedures are explicitly defined in advance, in order to ensure that the exercise is transparent and can be replicated. This practice is also designed to minimize bias.

Studies included in a review are screened for quality, so that the findings of a large number of studies can be combined. Peer review is a key part of the process; qualified independent researchers control the author's methods and results.

A systematic review must have:
  • Clear inclusion/ exclusion criteria
  • An explicit search strategy
  • Systematic coding and analysis of included studies
  • Meta-analysis (where possible)
How do Campbell systematic reviews differ from other systematic reviews?
  • Campbell reviews must include a systematic search for unpublished reports (to avoid publication bias).
  • Campbell reviews are usually international in scope.
  • A protocol (project plan) for the review is developed in advance and undergoes peer review.
  • Study inclusion and coding decisions are accomplished by at least two reviewers who work independently and compare results.
  • Campbell reviews undergo peer review and editorial review.