In case control study of buccal carcinoma-: (A) CA is commoner in zarda pan users than non users, (B) Zarda pan is a cause of buccal CA, (C) Zarda pan is associated with buccal CA, (D) If use of zarda pan is stopped, number of cases will reduce
Answer is C. Case control studies often retrospective studies are a common first approach to test causal hypothesis. In recent years case control study has emerged as a permanent method of epidemiological investigation. Both exposure and outcome has occurred before the study. Study proceeds backwards from effect to cause. It uses a control or comparison group to suppo or refute an inference (refer pgno:71 park 23 rd edition)