Hello,
We have some data on subjects who belong to 2 different groups. Each subject has measures taken at several time points, and these measures are correlated. The form of the data for each subject in one group is such that it follows an exponential curve: y=A*(1-exp(-x/t)) + C. Individuals in the second group follow more or less the same form, but there are clear differences between the two groups as a whole. My ultimate aim is to show differences between these groups. I am letting A, t and C be random effects (changing between subjects), but I also want to account for the covariance in the measures within each subject.
I have been trying to use PROC NLMIXED for this, but am unsure whether it accounts for within subject covariance (as in PROC MIXED). How can I specify this? Is a better option to go with the %NLINMIX macro?
Any help in this regard would be highly appreciated.
Thanks.