[R-sig-ME] nonlinear mixed longitudinal model

spencerg spencer.graves at prodsyse.com
Mon Apr 27 17:55:22 CEST 2009


Hello: 


      The definitive reference on "nlme" is Pinheiro, J.C., and Bates, 
D.M. (2000) "Mixed-Effects Models in S and S-PLUS" (Springer). 


      Moreover, the "nlme" package installed with R includes a "scripts" 
subdirectory containing files like "ch01.R", ..., "ch08.R", containing R 
scripts necessary to work all the examples in the book.  This is 
important, because the R syntax today is slightly different from that 
described in the book, and these script files work where the text in the 
book in very rare occasions gives the wrong answer without warning. 

      You can find this "scripts" directory via "system.file('scripts', 
package='nlme')". 


      This does not answer your entire question, but it might help. 


      Best Wishes,
      Spencer

Lee, MinJae wrote:
> Hello,
>
>
> 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;
> ll=(1-&cens)*(log((1/(sqrt(2*(3.14159)*se)))*exp((-1/(2*se))*((&coags-eta)**2))))
> +(&cens)*(log(probnorm((&coags-eta)/(sqrt(se)))));
> 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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> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
>
>




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