[R] glmmPQL probelm

[Prof Brian Ripley]

Nothing to do with glmmPQL (as traceback() would have shown you).

I think you are looking for ?try.

On Wed, 3 Sep 2003, Andrej Kveder wrote:

> Dear listers,
> 
> First let me appologize if the same mail arrives multiple times. Recently I
> had some probelms sending my e-mails to the list.
> 
> I encountered a problem when running glmmPQL procuedure doing multilevel
> modeling with a dichotomous outcome.
> Those are the two error messages I usually get:
> 
> Error in logLik.reStruct(object, conLin) :
>         NA/NaN/Inf in foreign function call (arg 3)
> 
> Error in solve.default(pdMatrix(a, fact = TRUE)) :
>         Lapack routine dgesv: system is exactly singular
> 
> The trick is that the model is a part of a simualtion run, which uses the
> same starting variance covariance matrix as a source for a mutlivariate
> normal simulated 2 level dataset. So the variations in the data set are just
> a part of the stochastic process. In the majority of the cases the model
> runs fine, while in some cases I get either of the two error messages. The
> model obviously cannot be identified. Does anybody have an idea why?
> The second question would relate to the handling of the problem. I don't
> even mind that much to have some models unidentified (of cours I would
> rather not have them). I would like to detect the possible problem
> beforehand in order to instruct the simulation run not to specifiy it. What
> is most annoying is that when an error occurs, the program stops the
> simulation run and not just skips the model results. Does anybody have an
> idea what to do about it? Any suggestions would be most helpfull. I can also
> send the R program file if that would help.
> 
> Thanks
> 
> Andrej
> 
> _________
> Andrej Kveder, M.A.
> researcher
> Institute of Medical Sciences SRS SASA; Novi trg 2, SI-1000 Ljubljana,
> Slovenia
> phone: +386 1 47 06 440   fax: +386 1 42 61 493
> 
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> 
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> 

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595