Confounder or Effect Modifier

Confounder or effect modifier?

· Evaluate a factor as a potential confounder or effect modifier

· Implement the 3 major criteria for confounding

Before beginning this activity, review the faculty notes and readings on bias, confounding, and effect modification. You will need to draw the confounding diagram to help visualize relationships. Work through each of the steps to evaluate confounding, constructing 2 x 2 tables and calculating measures of association as required.

Determining if a factor is a confounder or effect modifier is not always obvious by “common sense” thinking. As you work through the logic and evaluate each of the criteria for confounding, ask yourself if your interpretations make sense. If the factor was a confounder, in what direction did it influence the exposure-disease association? Is it a logical influence? If the factor was an effect modifier, does the difference in relationship between groups of the factor actually make sense (i.e., is it plausible)?