Editing Case–control study (section)

{{Short description|Type of observational study comparing two existing groups differing in outcome}}
{{cs1 config|name-list-style=vanc}}{{Use dmy dates|date=June 2020}}

A '''case–control study''' (also known as '''case–referent study''') is a type of [[observational study]] in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute. Case–control studies are often used to identify factors that may contribute to a medical condition by comparing subjects who have the condition with patients who do not have the condition but are otherwise similar.<ref name="url8. Case-control and cross sectional studies">{{cite journal |url=http://emj.bmj.com/content/20/1/54.full.pdf |title=8. Case–control and cross sectional studies |date=2003 |pmid=12533370 |access-date=5 March 2012 |journal=Emergency Medicine Journal |volume=20 |issue=1 |pages=54–60 |doi=10.1136/emj.20.1.54 |pmc=1726024 | vauthors = Mann CJ }}</ref> They require fewer resources but provide less evidence for causal inference than a [[randomized controlled trial]]. A case–control study is often used to produce an [[odds ratio]]. Some statistical methods make it possible to use a case–control study to also estimate relative risk, risk differences, and other quantities.<ref>{{Cite journal |last1=King |first1=Gary |last2=Zeng |first2=Langche |date=2002-05-30 |title=Estimating risk and rate levels, ratios and differences in case–control studies |url=https://onlinelibrary.wiley.com/doi/10.1002/sim.1032 |journal=Statistics in Medicine |language=en |volume=21 |issue=10 |pages=1409–1427 |doi=10.1002/sim.1032 |pmid=12185893 |s2cid=11387977 |issn=0277-6715|url-access=subscription }}</ref>