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Observational Studies 

Observational Studies
Study Design and Statistics

Margaret A. Winker

and Stephen J. Lurie

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date: 19 January 2020

In an observational study, the researcher identifies a condition or outcome of interest and then measures factors that may be related to that outcome. Although observational studies cannot lead to strong causal inferences, they may nonetheless suggest certain causal hypotheses. To infer causation in observational studies, investigators attempt to establish a sequence of events if event A generally precedes event B in time, then it is possible that A may be responsible for causing B. Such studies may be either (the investigator tries to reconstruct what happened in the past) or prospective (the investigator identifies a group of individuals and

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