What is a cohort study?

A cohort study is an observational research method where a group of individuals, known as a cohort, is followed over a period of time to assess various outcomes related to specific exposures or characteristics. This type of study design is particularly valuable for understanding how certain factors may influence health outcomes or the development of diseases within the cohort.

In a cohort study, researchers collect data from the participants at the beginning of the study to identify their exposures, then continue to monitor these participants over time to observe any changes in their health status or the occurrence of particular outcomes. This longitudinal approach allows for the establishment of a timeline of events which can provide insights into cause-and-effect relationships.

The other options describe different types of research methods that do not fit the definition of a cohort study. An experimental study primarily involves interventions to test hypotheses, a literature review aggregates and analyzes existing research rather than tracking new data, and validity evaluation assesses whether the findings of one study are applicable to another context, which does not involve following a cohort in a longitudinal manner.