In case control study of buccal carcinoma-
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)
CA is commoner in zarda pan users than non users
Zarda pan is a cause of buccal CA
Zarda pan is associated with buccal CA
If use of zarda pan is stopped, number of cases will reduce
Epidemiology