# mh calc

… a statistical test of stratified selections

### mh calc allows testing of association between selection and protected status, controlling for up to 18 tiers in a third variable.

**mh calc** computes the Mantel-Haenszel statistic, common odds ratio, and Breslow-Day test of homogeneity. Odds ratios and Fisher's exact test are computed for each tier.

### Overview of Process

Data entry in **mh calc** is similar to entering 2x2 tables in **square**, with four cell values for each tier. *Note:* **mh calc** allows up to 18 tiers, but any tier with no data (*i.e*., all zeros) is ignored, and any tier with a zero marginal is also ignored.

For example, a tier would have a zero marginal if no women applied in that tier, or if there were no selections in that tier. Edit boxes are provided to label the tiers, and there is a dialog box to create row and column labels.

### In the example below …

Plaintiff alleges that MH Clothing Co. failed to promote its female employees on a equal basis with their male collegues. MH Clothing claims that each store treated employees the same.

**mh calc** was used to analyze the relation between sex and promotion, controlling for store. The Mantel-Haenszel χ² of 5.90 yields a probability value of 0.015. Thus, there is less than a 2% chance that the association between sex and promotion is spurious. This would generally be recognized as statistically significant. Also, the Breslow-Day statistic (1.83, p=0.76) is not significant, indicating that homogeneity is not an issue.

*— click image to expand*