[R] lme() doesn't converge on IGF example

[David Daniel]

Running the Chapter 4 examples in Pinheiro & Bates' "Mixed-Effects  
Models in S and S-PLUS" (2000), I get a message that the default  
optimizer doesn't converge, but using "optim" for the optimizer  
results in convergence:

> > library(nlme)
> > fm1IGF.lis <- lmList(IGF)
> > fm1IGF.lme <- lme(fm1IGF.lis)
> Error in lme.formula(fixed = conc ~ age, data = IGF, random = list 
> (Lot = c(-0.741604809797216,  :
> 	nlminb problem, convergence error code = 1; message = iteration  
> limit reached without convergence (9)
> >
> > fm1IGF.lme <- lme(fm1IGF.lis, control= list(opt="optim"))

I wouldn't have expected the default optimizer to not work with an  
example from this text.  Not knowing anything about the optimizers,  
I'm wondering if this is expected or known behavior, or if there are  
tips for getting it to converge other than changing optimizers?

nlme Version:       3.1-80

> > R.Version()
> $platform
> [1] "i386-apple-darwin8.9.1"
>
> $arch
> [1] "i386"
>
> $os
> [1] "darwin8.9.1"
>
> $system
> [1] "i386, darwin8.9.1"
>
> $status
> [1] ""
>
> $major
> [1] "2"
>
> $minor
> [1] "5.0"
>
> $year
> [1] "2007"
>
> $month
> [1] "04"
>
> $day
> [1] "23"
>
> $`svn rev`
> [1] "41293"
>
> $language
> [1] "R"
>
> $version.string
> [1] "R version 2.5.0 (2007-04-23)"

----------------------------------
David Daniel
Associate Professor
University Statistics Center
New Mexico State University

ddaniel at nmsu.edu