The study of smoking as a cause of lung cancer, 90 cases were taken, 75 were smokers and among 100 controls 40 were smokers. Calculate the odds ratio ?

Ans. is 'c' i.e., 7.5 Odds ratio is cross product of entries in the table. So, it is very impoant to make a correct table construct ? i) History of exposure (risk factor) is arranged on left column (row). ii) Disease is arranged on the top ? a) Cases in middle column (row) b) Controls in right column (row)