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Systematic Reviews

This is a guide to understanding systematic reviews and other evidence synthesis methods. Links to resources and information about the Libraries' Systematic Review Service is included.

Why Have Inclusion/Exclusion Criteria?

After developing your PICO question, it is critically important for you and your team to establish a set of "rules" for selecting, then screening the articles located during your database and internet searches. These rules are called the inclusion/exclusion criteria. Be aware that you may introduce bias into the final review if these are not used thoughtfully and adhered to regardless of outcome. The purpose of using inclusions/exclusion criteria "is to minimize ambiguity and reduce the possibility of poor reproducibility". This criteria should not be too narrow or too loose. 

McDonagh M, Peterson K, Raina P, et al. Avoiding Bias in Selecting Studies. 2013 Feb 20. In: Methods Guide for Effectiveness and Comparative Effectiveness Reviews [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2008-. Available from:

A Visual Representation


Ghezzi-Kopel, Kate. (2019, September 16). Developing your research question. (research guide). Retrieved from