I am looking to determine whether patient's total number of prescriptions (RxTotal) differs by membership within 3 possible groups (ie run an ANOVA), and if so, to determine which groups differ (ie run multiple comparisons). My data is non-normal (Shapiro Wilk p<.0001) and the groups have unequal variances (Levene p<.0001). My group Ns are 113, 202, and 90. I understand that ANOVA is fairly robust against violations of normality and HOV as long as each group has equal Ns. I do not know if the Ns of my 3 groups could possibly be considered "equal" so I have chosen to go with using Welch's F statistic (p<.0001), although I am open to feedback to take other routes. I have read that the Games-Howell multiple comparisons test works well with HOV violations, and that it is the Welch's equivalent of the Tukey post hoc test. I have searched at length and cannot figure out what the syntax would be for running Games-Howell multiple comparisons tests in SAS. Is this perhaps because it requires a macro, or is there an option built into a standard SAS procedure that I have not found?
This is my syntax for running the Welch ANOVA, and the Tukey post hoc tests (which I am inclined not to use):
proc glm data=cutoffs1;
model rxtotal = group;
means group / welch tukey;