PROC FREQ computes Cochran-Mantel-Haenszel statistics, controlling for
Gender. For stratified 2×2 contingency tables, these statistics include
estimates of the common relative risk and the Breslow-Day test for homogeneity
of the odds ratios. For a stratified 2×2 table, the three CMH statistics
test the same hypothesis. The significant p-value (.004) indicates
that the association between treatment and response remains strong after adjusting
for gender.
The large p-value for the Breslow-Day test (.222) indicates
no significant gender difference in the odds ratios. Because this is a prospective
study, the relative risk estimate assesses the effectiveness of the new drug.
The probability of migraine improvement with the new drug is just over two
times the probability of improvement with the placebo.
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