<prompt> 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 ?24.57.510  <response>: 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 