In the paper [Gold E,Gordis L,Tonascia J,et al.Risk factors for brain tumors in children.Am J Epidemiol.1979;109(3) :309-319],investigators conducted a case-control study to identify risk factors for brain tumors in children.Children with brain tumors were compared with two groups of controls: The first control group,called normal controls,consisted of children with no known malignant disease.The second control group,called cancer controls,consisted of children with malignancies other than brain tumors.What is the benefit of using multiple controls in case-control studies?

A) This may reduce the recall bias from participants.
B) This may reduce the selection bias for participation.
C) This may reduce the potential confounders from investigators.
D) This may reduce the placebo effect from participants.
E) None of above.

Question

Zybrea Knight · Accepted Answer

Final Answer : A, Explanation :  Cases are more likely to recall exposures that they believe may have contributed to the outcome.In this case,cancer controls are also likely to remember previous exposures,then we may reduce recall bias.This may reduce the selection bias for participation might be guaranteed by choosing community controls instead of hospital controls.This may reduce the potential confounders from investigators is acquired by randomization.This may reduce the placebo effect from participants is an explanation about blinding (masking) in clinical trial.

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