Performing an NxP Test for Association

Sometimes you have more than two levels of groups or responses and you want to test for association. In this case you have an NxP table that looks like this  

Here you can still use the Pearson chi-square test as shown in the 2x2 table example as long as your response variable is nominal and merely descriptive. If your response variable is ordinal, meaning that it is an ordered sequence, and you can use a parametric test, then you should use the Mantel-Haenszel test statistic for parametric tests of association. For instance, if in our previous example the variable called headache was coded as a 2 when the patient experienced extreme headache, a 1 if mild headache, and a 0 if no headache, then headache would be an ordinal variable. You can get the Mantel-Haenszel /pvalue by running the following SAS code  

Your Mantel-Haenszel /7-value is found in the P MHCHI variable in the pvalue data set. 

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