What is a "cohort study"?

A cohort study is a specific type of observational study design where a group of individuals, called a cohort, is followed over a period of time to observe the development of particular outcomes or conditions. This type of study allows researchers to assess the association between exposure factors (like lifestyle choices or environmental influences) and the occurrence of health-related events (such as diseases).

In conducting a cohort study, the researcher identifies a group of participants who share certain characteristics or experiences and then tracks their health outcomes over time. This can be especially useful in identifying risk factors for diseases, as it provides data on how exposures affect the incidence of conditions within the cohort.

This method contrasts with other study designs. For instance, experimental studies involve assigning participants randomly to different groups to test the impact of an intervention, which is a different approach than simply observing a population over time. Observational studies that compare individuals with and without a condition may focus on case-control studies, which look backward from outcomes to potential exposures rather than following cohorts over time. Lastly, while investigating vaccine efficacy could involve a cohort study, it does not encapsulate the definition of a cohort study itself.