Cohort study is better than case control study in all ways except -

Ans. is 'b' i.e., Lesser time spent o Cohort study is more time consuming,o Cohort study is prospective study,o Chances of bias are high in case-control study.Main differences between case control and cohort studiesCase control studyCohort study1. Proceeds from ''effect to cause"Proceeds from "cause to effect"2 Starts with the diseaseStarts with people exposed to risk factor or suspected cause3. Tests whether the suspected cause occurs more frequently in those with the disease than among those without the diseaseTests whether disease occurs more frequently in those exposed, than in those not similar exposed4. Usually the first approach to the testing of a hypothesis, but also useful for exploratory studiesReserved fortesting of precisely formulated hypothesis5. Involves fewer number of subjectsInvolves larger number of subjects.6. Yields relatively quick resultsLong follow-up period often needed, involving delayed results.7. Suitable for the study of rare diseases.Inappropriate when the disease or exposure under investigation is rare.8. Generally yields only estimate of RR (odds ratio)Yields incidence rates, RR as well as AR.9. Cannot yield information about diseases other than that selected for studyCan yield information about more than one disease outcome.10. Relatively inexpensiveExpensive