Hi all,    I want to apply a CMH test to compare Aortic regurgitation (AR) between two groups. Aortic regurgitation is an ordinal variable (tvrn) with 7 modalities (1-None, 2-Trace, 3-Mild, 4-Mild to moderate, 5-Moderate, 6-Moderate to severe, 7-Severe). I observe different p-values for CMH Row Mean Scores Differ test if the ordinal variable is defined as a character variable or as a numeric variable when there is no patient in one of the intermediate level. I would understand the reasons of such difference and be sure to use the correct format this ordinal variable. Thank you    proc sort data=essai2 ; by tvrn trt; run; proc freq data=essai2 order=data; tables trt*tvrn /cmh ; run; Example: No patient with 5-Moderate or 6-Moderate to severe AR Results when the ordinal variable is in character. Results when the ordinal variable is in numeric:     ... View more