Inclusion and exclusion criteria set the boundaries for your systematic search and consider many different factors. These can include the topic, the research methods of the studies, specific populations, settings, date limits, geographical areas, types of interventions, or something else. The inclusion criteria is everything a study must have in order to be included. The exclusion criteria are the factors that would make a study ineligible to be included. They are determined after setting the research question (usually before searching).