Hi R user, I have a question about "nlmer". Can I specify the multilevel random effects in the the nlmer? For example, level 1 is "hospital" and level 2 is patient, so nlmer(response~SSfol(Dose,Time,lke,lka,lcl)~(lke+lka+lcl|hospital)~(lke+lka+lcl|patient%in%hospital), data=health, start=c(lke=-2.5,lka=0.5,lcl=-3),verb=1)) I can do it in the nlme but I still don't know how to get it in nlmer! many thanks in advance Chunhao