In a prospoective study comprising 10,000 subjects, 6000 subjects were put in beta carotene and 4000 were not. 3 out of the first 6000 developed lung cancer and 2 out of the second 4000 developed lung cancer. What is the interpretation of the above results?

This is a prospective study or coho study. Risk is estimated as relative risk and attributable risk. Relative risk =incidence of disease in exposed/incidence of disease in unexposed. incidence in exposed = 3/6000 Incidence in unexposed =2/4000 Relative risk=1 Relative risk = 1 implies no association between exposure and disease under study; no association between beta-carotene intake and lung cancer Ref: Parks textbook of preventive and social medicine, 23rd Edition Pg no: 78