<prompt> Cross-product ratio is estimated by ?Coho studyCase-control studyCross sectional studyField trial  <response>: Ans. is b i.e., Case-control studyOdds - ratio cross product ratioFrom a case control study odds ratio can be derived which a measure of the strength of association between risk factor and outcome.Odds ratio is closely related to relative risk which is analysed in coho study 4 odds ratio represents only an estimate of relative risk. 