Best epidemiological study to know Causality is:: (A) Coho study, (B) Case control study, (C) Cross sectional study, (D) Ecological study
Answer is A. Temporal association Implies 'cause precedes effect' or 'effect follows cause'. Is 'most impoant criterion' of casual association. Is ' best established by a coho study' (Especially concurrent coho study) as coho study is forward study.