Biostatistics & Research · single question
What type of study is a COHORT study?
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Correct answer: D. Prospective or retrospective observational study following a group over time
A cohort study follows a group (cohort) of people over time, comparing outcomes between exposed and unexposed groups. It can be PROSPECTIVE (forward in time) or RETROSPECTIVE (looking back at records). Cohort studies are observational — no randomization or intervention. They provide strong evidence of causation when prospective.
- A. Incorrect. A cross-sectional study measures both exposure and outcome at a SINGLE point in time.
- B. CORRECT. A cohort study follows exposed and unexposed groups over time to compare incidence of outcomes.
- C. Incorrect. An RCT involves random assignment to intervention or control groups — not observational.
- D. Incorrect. A case-control study selects participants based on OUTCOME (cases vs. controls) — the reverse of a cohort design.
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