Hi Steve @sld , Thank you for the code provided.  I have a few questions for you if you could help.  1. In your code provided, I understand year and month are within-subject factors but was treatment?   2. The whole purpose to evaluate the variance (heterogeneity) of group.  In the GLIMMIX example below, I am able to estimate a variance matric for each rf1, but am not sure how to add a second group.  How would you recommend manipulating the code?   3. My factors are imbalanced.  Factor levels of rf2 vary by rf1.  I do not necessarily need a 20x20 (point by point) but would like an estimated variance of rf1 and rf2 (potentially rf1xrf2) and group.  Neither of the models below get me that. Would a random statement for each be better? 4. I am familiar with post plots of lsmeans but do you know of a good post plot to display the variances aside from a table? Thank you.   proc mixed data=data covtest; class rf1 rf2 subj group; model y = group|rf1|rf2 / ddfm=kr; repeated rf1 rf2/subject=subj(group) type=un@cs r rcorr group=group; run; proc glimmix data=data; nloptions gconv=0; class rf1 rf2 subj group; model y = group|rf1|rf2 / ddfm=kr; random rf2 / subject=subj(group) group=rf1 type=ar(1) v residual; run; proc mixed data=y covtest; class rf1 rf2 subj group; model y = group|rf1|rf2 / ddfm=kr; random intercept/subject=subj group=group v vcorr; repeated rf2/subject=subj*rf1 type=ar(1) group=group; run;         ... View more

I beleive I was emailing you as you were posting. I am new to posting on this site. I will look through these and get back with any questions. Thank you. ... View more

Thank you for your responses.  I'dl ike to specify that the residuals could differ across group.  I am trying to ask the question, does the variance differ across groups (independent factor) while maintaining the structure/design features of the datset.  So, I think I would like to determine whether the residual variance differs across group while maintaining this two-way design.  My mixed model could look something like this but I am unsure how to specify this in glimmix, given that GLIMMIX does not allow repeated statement. I understand how to do this with one repeated factor but not 2.  Is this more clear? group=independent group; rf1=first within-subject condition; rf2=second within-subject factor such that rf1xrf2 create a unique combination. I first need to specify the residual structure in glimmix correctly and then will use the covtest.   proc mixed data=data covtest; class id group rf1 rf2; model y=group; random subj rf1(id) rf2(id)/ v vcorr group=group; run;     ... View more