<prompt> Best study is ?Case-control studyCoho studyMeta-analysisRCT  <response>: Ans. is c i.e., Meta-analysis Here are the different epidemiological studies with decreasing order of accuracy to test the association between risk factor and disease : ? Systematic review and meta-analysis - Overall most reliable Randomized controlled trials controlled clinical trails - Most reliable individual study. Retrospective Non-concurrenthistoric Coho study. Prospective concurrent Coho study. Case control study Cross-sectional study Ecological study 