> Hello. I'm trying to look at the pre-post drug administration effect on > the time course of c-peptide levels during an experimental procedure. I'd > like to set up a simple mixed effects model (oxymoron) using the following > parameters : CP= c-peptide conc., TIME = time of CP measurement > (0,1,2,3,4,5,6,7,8,9), EXP=Pre or Post classification, ID=subject id. > There are nine subjects in the dataset. > > When I use the following syntax - > > proc mixed; > class id time exp; > model cp=exp time exp*time; > repeated time exp/sub=id type=cs; > > I get the error - > > ERROR: Only one REPEATED effect is allowed with this covariance structure. > > I've tried other covariance structures (UN, Ar(1))and have gotten the same > message. > Any suggestions or useful references appreciated. Thanks in advance. > > Denis C. Muller > National Institute on Aging > Baltimore, MD 21224-2735 > >