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longitudinal study, prospective study, retrospective study
In cohort studies, individuals who share certain characteristics (a diagnosis, for example), or subsets of them are followed up to record their experiences, including whether they have outcomes of interest.
For example, people who were exposed or not exposed (or exposed at different levels) to a particular treatment, or other factor of interest could be compared.
A prospective follow-up (cohort) study assembles participants and follows them into the future. A retrospective (or historical) follow-up (cohort) study identifies people from past records and follows them from the time of those records to the present.
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