<prompt> In a study there were 35 cases of lung carcinoma and 82 controls were there. On taking history, 33 cases had positive history of smoking and 55 individuals among controls had positive history of smoking. What is the odds ratio-82050100  <response>: Ans. is a i.e., 8 Odds ratio is cross product of entries in the table. So, it is very important 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 rowb Controls in right column row Disease Present casesAbsent controlsExposure presentabExposure absentcdTotala cb dComing to question Cases Total cases 35 Among these smokers 33 a Non smokers 35 - 33 2 c Controls Total 82 Smokers 55 b Non smokers 82 - 55 27 dThis data can be arranged - Lung cancerPresent casesAbsent controlsSmoking present3355abSmoking absent227cdTotal35a c82b d Odds ratio ad---bc 33 x 27---55 x 2 8.1 