This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: DNB 2018, Subject name: Social & Preventive Medicine
[{'content': 'Cross product ratio is used in:- \nSelect and explain. \nA. Cross- sectional study, B. Case control study, C. Coho study, D. Ecological study', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Framework of a case control study (The 2 x 2 contigency table) Suspected or risk factors Cases (Disease present) Control (Disease absent) Present Absent ac bd a+c b+d Cross product ratio is another name for Odds ratio. It used to calculate strength of association between risk factor and outcome in case of case control studies. Odds Ratio (OR) = (a x d)/(b x c) Since it involves cross multiplying the values in the 2x2 Contingency table, it is called cross product ratio In coho study , Relative Risk (or Risk Ratio) is determined Cross sectional studies deal with determining prevalence of disease Ecological study is used to determine correlation', 'role': 'assistant'}]