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Systematic Reviews: A How-To Guide

Step 2: Define Selection Criteria

  • Based on your research question, decide on the inclusion/exclusion criteria that will be applied to your search results.
  • Determining these criteria in advance help minimize bias and will assist with searching the literature.

Examples of Possible Selection Criteria

  • Study population (i.e. age, sex, race, presence/absence of disease)
  • Setting (i.e. hospital inpatients, nursing home, outpatients)
  • Study size (i.e. population N > 100)
  • Study design (i.e. randomized controlled trials, observational studies) 
  • Study language (i.e. English-only)

The criteria you choose will ultimately depend on your research question. However, you do have to set criteria wisely. If selection criteria is too narrow, you can risk missing relevant studies. If selection criteria is too broad, the studies may be too different to compare and synthesize. 

More Information on Selection Criteria