Biostatistics & Research · single question
A group of people with a habit of smoking is followed for 8 years to check the incidence of cancer. Which type of study is this?
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Correct answer: C. Cohort study
- A. A cross-sectional study measures both exposure and outcome AT THE SAME POINT IN TIME — it cannot follow people over 8 years.
- B. An experimental study involves INTERVENTION — the researcher assigns the exposure. Following smokers who already smoke is an OBSERVATIONAL cohort, not an experiment.
- C. A COHORT STUDY follows a defined group (cohort) of people WITH a specific exposure (smokers) FORWARD IN TIME to observe the development of outcomes (cancer). Key features: longitudinal, prospective (or retrospective from records), measures INCIDENCE. This is the classic cohort study design — following smokers over 8 years to track cancer development.
- D. A case-control study identifies people WITH the disease (cases) and WITHOUT the disease (controls) and LOOKS BACK at exposures — the opposite direction from a cohort study.
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