[R-sig-ME] nonlinear mixed longitudinal model

Lee, MinJae leem2 at upmc.edu
Mon Apr 27 05:12:18 CEST 2009


I was trying to convert the Proc nlmixed SAS to nlme in R.

especially, I'm considering the approach of Thiébaut and *Gadda( *Mixed models for longitudinal left-censored repeated measures in SAS program:

proc nlmixed

parms alpha=1 beta1=1 beta2=1   s11=0.5 s22=0.5 se=1;
bounds 0<=s11, 0<s22, 0<se;
eta=alpha+beta1*&gp+beta2*day+ u1+day*u2;
model &coags ~ general(ll);

random u1 u2 ~ normal([0,0],[s11,0,s22]) subject=subjectid;

I know there are a lot of differences between them(nlmixed vs nlme), but I really need to convert this program to R.

could you please give any advise for me?

is there any appropriate packages in R for this model?

Thank you so much in advance,

Minjae Lee

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