Module 9: Confounding and MH Method
With categorical data, we are classifying data instead of measuring it. As a review:
Notice we never use a z test, a t test is almost always more appropriate even for large samples. Likewise, for dichotomous outcomes could use a z-test but a chi-square test is usually used in practice. Chi-square reflects categorical outcomes.
chi-square = sum((obs-exp)2 / exp), df=n-1; where n is the number of random variables or categories.
Mantel-Hansel Method
The MH Method is a way to stratify by confounding variables and pool the data for a combined decision, provided that the confounder is not an effect modifier.