Thaink about what you need here--since growth is assumed to be normally distributed (at least to have Gaussian error), you probably don't need method=quad. The REML estimates should give what you are looking for. However, if you do want to include the residual error in the optimization, then you could remove the residual option from the first RANDOM statement.
Steve Denham
Catch up on SAS Innovate 2026
Nearly 200 sessions are now available on demand with the SAS Innovate Digital Pass.