This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Confounding cannot be removed by? 
Select and explain. 
A. Assign confounders to both cases and controls, B. Stratification, C. Matching, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: All of the above REF: Park 20' edition page 68, http://en.wikipedia.org/wiki/Confounding There are various ways to modify a study design to actively exclude or control confounding variables In Case-control studies assign confounders to both groups, cases and controls, equally. In Coho studies matching is often done by only admitting ceain age groups or a ceain sex into the study population, and thus all cohos are comparable in regard to the possible confounding variable Stratification: Controlling for confounding by measuring the known confounders and including them as covariates in multivariate analyses