If a researchers in an observational study attempts to control for a confounding variable, is it more likely that the resulting confidence interval will be wider or narrower than the confidence interval when he/she didn't control for the confounding variable?
A)It will probably be wider.
B)It will probably be narrower.
C)It will have to be disregarded; you can't adjust or control for confounding variables after the fact.
D)There is no way of knowing.

Question

Quizplus · Accepted Answer

Controlling for a confounding variable reduces bias and makes the confidence interval more precise, resulting in a narrower confidence interval.

If a Researchers in an Observational Study Attempts to Control