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'''Causal inference''' is the process of drawing a conclusion about a [[causal]] connection based on the conditions of the occurrence of an effect. The main difference between causal inference and inference of [[association (statistics)|association]] is that the former analyzes the response of the effect variable when the cause is changed.<ref name=Pearl_Journal>{{cite journal|last=Pearl|first=Judea|title=Causal inference in statistics: An overview|journal=Statistics Surveys|date=1 January 2009|volume=3|issue=|pages=96–146|doi=10.1214/09-SS057|url=http://ftp.cs.ucla.edu/pub/stat_ser/r350.pdf}}</ref><ref name=Morgan_book>{{cite book|last=Morgan|first=Stephen|author2=Winship, Chris|title=Counterfactuals and Causal inference|publisher=Cambridge University Press|year=2007|isbn=978-0-521-67193-4}}</ref> The science of why things occur is called [[etiology]].  Causal inference is an example of [[causal reasoning]].

'''Causal inference''' is the process of drawing a conclusion about a [[causal]] connection based on the conditions of the occurrence of an effect. The main difference between causal inference and inference of [[association (statistics)|association]] is that the former analyzes the response of the effect variable when the cause is changed.<ref name=Pearl_Journal>{{cite journal|last=Pearl|first=Judea|title=Causal inference in statistics: An overview|journal=Statistics Surveys|date=1 January 2009|volume=3|issue=|pages=96–146|doi=10.1214/09-SS057|url=http://ftp.cs.ucla.edu/pub/stat_ser/r350.pdf}}</ref><ref name=Morgan_book>{{cite book|last=Morgan|first=Stephen|author2=Winship, Chris|title=Counterfactuals and Causal inference|publisher=Cambridge University Press|year=2007|isbn=978-0-521-67193-4}}</ref> The science of why things occur is called [[etiology]].  Causal inference is an example of [[causal reasoning]].

Epidemiological studies employ different [[epidemiological method]]s of collecting and measuring evidence of risk factors and effect and different ways of measuring association between the two. A [[hypothesis]] is formulated, and then [[Statistical hypothesis testing|tested with statistical methods]]. It is [[statistical inference]] that helps decide if data are due to chance, also called [[random variation]], or indeed correlated and if so how strongly. However, [[correlation does not imply causation]], so further methods must be used to infer causation.{{Citation needed|date=May 2019}}

Epidemiological studies employ different [[epidemiological method]]s of collecting and measuring evidence of risk factors and effect and different ways of measuring association between the two. A [[hypothesis]] is formulated, and then [[Statistical hypothesis testing|tested with statistical methods]]. It is [[statistical inference]] that helps decide if data are due to chance, also called [[random variation]], or indeed correlated and if so how strongly. However, [[correlation does not imply causation]], so further methods must be used to infer causation.{{Citation needed|date=May 2019}}