Inclusion and exclusion criteria (aka those characteristics that might cause you to include or exclude a study from your review) should be decided upon during the protocol stage of a review. These criteria can be based on many factors, and should be informed by your research question and objective. This graphic provides a great overview of some of the common factors considered for inclusion or exclusion.
Deciding on inclusion/exclusion criteria at the protocol stage is helpful to ensure that your team has a clear understanding of what will or will not be included in the review across all members.
After you have found all the articles considered for inclusion, your team will begin screening articles based on this inclusion and exclusion criteria, and documenting your reasons for including/excluding certain studies. See the Screen Your Articles tab for more information on this process.