Why not: proc mixed data = mjuse covtest noitprint; class id studyday; model marijuana = studyday / solution cl outp = intp outpm = intpm ; repeated studyday /subject=id type = ar(1); random intercept/subject=id; run; I guess I don't understand the coding for time01, so I automatically revert to fitting studyday. This all assumes that marijuana is a continuous variable, and that everything has NID (0, sigma**2) errors. If your response variable is something different, or has a large skew, you may need to consider a generalized mixed model. Steve Denham
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