[R] nlme questions

[Spencer Graves]

	  Both your questions seem too vague to me.  You might get more useful 
replies if you provide a simple example in a few lines of R code that a 
reader could copy from your email into R and see the result (as 
suggested in the posting guide! "www.R-project.org/posting-guide.html"). 
  The process of preparing such a simple example might by itself provide 
the insight you desire.  Alternatively, you might work line by line 
through the code for the R function you are using.  Also, if you don't 
have Pinheiro and Bates (2000) Mixed-Effects Models in S and S-PLUS 
(Springer), I suggest you get it;  it is excellent for things like this.

	  I'm sorry I couldn't help more.  	
	  spencer graves	

Christian Mora wrote:

> 
> 
> 
> Dear R users;
> 
> Ive got two questions concerning nlme library 3.1-65 (running on R 2.2.0 /
> Win XP Pro). The first one is related to augPred function. Ive been working
> with a nonlinear mixed model with no problems so far. However, when the
> parameters of the model are specified in terms of some other covariates,
> say treatment (i.e. phi1~trt1+trt2, etc) the augPred function give me the
> following error: "Error in predict.nlme(object,
> value[1:(nrow(value)/nL),,drop=FALSE], : Levels 0,1 not allowed for trt1,
> trt2". The same model specification as well as the augPred function under
> SPlus 2000 run without problems. The second question has to deal with the
> time needed for the model to converge. It really takes a lot of time to fit
> the model on R in relation to the time required to fit the same model on
> SPlus. I can imagine this is related to the optimization algorithm or
> something like that, but I would like to have a different opinion on these
> two issues.
> 
> Thanks in advance
> 
> Christian Mora
> 
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-- 
Spencer Graves, PhD
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