Table 2.

Formulas for calculating search recall^a and precision^b .

Search in PubMed or Google Scholar for a clinical question	Relevant articlesc	Nonrelevant articles
Articles found	TP	FP
Articles not found	FN	TN

^aSearch recall TP/(TP + FN): the number of relevant articles found as a proportion of the total number of relevant articles.

^bSearch precision TP/(TP + FP) (also referred to as the positive predictive value in diagnostic test terminology): the number of relevant articles found as a proportion of the total number of articles found.

^cFor each search, the set of relevant articles were the collection primary studies included in the original systematic review from which the clinical question was derived.