This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Classification, Coho Study, Subject name: Social & Preventive Medicine
Of the different epidemiological study designs available to test the association between risk factor and disease, the best design is of- 
Select and explain. 
A. Case-control study, B. Ecological study, C. Coho study, D. Cross-sectional study
C: Coho study
Answer: C: Coho study 
Explanation: - Coho study gives the strongest evidence of association. - Strength of association in coho study is calculated by: Relative risk - Best indicator as it has lower biases as compared to other studies. Attributable risk. Population attributable risk.