Following are true about case control study except-

Case control studies often retrospective studies are 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 Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 79