I have a data on a 3 way cross over design with two treatments(A and B, B is given twice) applied on 16 subjects in three different periods using three sequences. So i have analyzed it using Proc mixed procedure in SAS 9.1 given below:
PROC MIXED data=data ;
CLASSES SEQ SUB PER TRT;
MODEL Y=SEQ PER TRT /DDFM=SATTERTH;
RANDOM TRT/TYPE=FA0(2) SUB=SUB G;
ESTIMATE 'T vs. R' TRT 1-1/CL ALPHA=0.1;
Now in output, residual value is coming for both treatments A and B in Covariance parameter estimate while B is the only treatment repeated. So my question is how am i getting residual value for both the treatments. Is it correct or there is some problem with my SAS codes.