Of the different epidemiological study designs available to test the association between risk factor and disease, the best design is of
High-Yield Explanation
Coho study is also known as incidence study. The cohos are identified prior to the appearance of disease under investigation. The study group so defined are observed over a period of time to determine the frequency of disease among them. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 83