Hello, When using different variables order in proc mixed, I get different results. For example with the following SAS program: proc mixed data=table;      class trt center study visit subject;      model change = baseline visit trt center*study trt*visit baseline*visit;      repeated visit / type=un subject=subject;      lsmeans trt*visit / pdiff cl alpha = 0.05; run; the model doesn't converge, whereas if the variables in the model statement are in the following order: model change = visit trt center*study trt*visit baseline baseline*visit; (the only difference is the order of the baseline variable) then the model converges . How this could be explained as the variables order should not impact the results? Many thanks for your help. Kind regards, ... View more