When is the cohort formed for a Retrospective Study? In the past Today In the future

Understanding Cohort Formation in a Retrospective Study

In a retrospective study, the cohort is formed by identifying a group of participants based on prior exposure or characteristics related to a specific outcome that has already occurred.

1. Cohort's Time Frame: Unlike prospective studies where a cohort is followed into the future, in retrospective studies, researchers look back in time to gather historical data.
2. Identifying Past Exposures: The cohort is selected based on past exposure to a risk factor or intervention and the subsequent outcome that already has been documented.

Conclusion

Therefore, the cohort in a retrospective study is formed in the past. Researchers use existing records, databases, or previous studies to identify individuals who meet the criteria of the study based on past exposures and outcomes.