What is a case control design?

An observational design where patients are selected on the basis of an outcome variable. Contrast this with a cohort design. Researchers select cases, a group of patients with a specific outcome (e.g., brain cancer) and controls, a second group without that outcome. The controls will often come either from the same hospital as the cases but with an unrelated condition, or from the same community as the cases. Here is an example:

• In Bonita et al 1999, "Cases were obtained from the Auckland stroke study, a population-based register of acute stroke. Controls were obtained from a cross-sectional survery of major cardiovascular risk factors measured in the same population." The researchers examined the relationship between passive smoke exposure and stroke.

This webpage was written by Steve Simon on 2005-10-11, edited by Steve Simon, and was last modified on 2008-07-08. This page needs minor revisions. Category: Definitions, Category: Research designs.