Cohort Studies: Retrospective Studies

In retrospective studies, subjects are divided into groups and the individual groups are categorized by certain characteristics. The outcomes are then measured in the present time.

Example: An epidemiologist wants to know whether people of the Christian faith have lower incidences of cancer than people with Muslim faith, so she conducts a retrospective cohort study. From the sample, she takes 2 groups- each group is characterized by have the faith of either Christianity or Muslim. She then measures the incidence of cancer in each group.