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List:       r-sig-mixed-models
Subject:    Re: [R-sig-ME] Cholmod warning
From:       Iker Vaquero Alba <karraspito () yahoo ! es>
Date:       2011-07-24 17:15:48
Message-ID: 1311527748.66745.YahooMailNeo () web27006 ! mail ! ukl ! yahoo ! com
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s.hatchcoltailmodel1.76<-lmer(nhatch1~sex+tlength+brithr+briventral+cond+weatherpc1+we \
atherpc1:briventral+weatherpc1:cond+(1|site/pair)+(1|year),family=poisson,na.action=na.omit,verbose=TRUE)


  0:     129.32699:  1.05525 0.617213 0.242091  2.11758 -0.0668442 0.00235620 \
0.00296124 0.000930340 -0.619141 0.622250 0.00267117 -0.537532  1:     129.32699:  \
1.05525 0.617213 0.242091  2.11758 -0.0668442 0.00235620 0.00296124 0.000930340 \
-0.619141 0.622250 0.00267117 -0.537532

Mensajes de aviso perdidos
1: In mer_finalize(ans) :
  Cholmod warning 'not positive definite' at file:../Cholesky/t_cholmod_rowfac.c, \
                line 432
2: In mer_finalize(ans) :
  Cholmod warning 'not positive definite' at file:../Cholesky/t_cholmod_rowfac.c, \
                line 432
3: In mer_finalize(ans) : false convergence (8)


   I thought it could be overparametrized, but in that case, why don't I get any \
error with the maximum model, which has much more parameters to estimate? 


   Thank you very much. Iker



________________________________
De: Douglas Bates <bates@stat.wisc.edu>

CC: "r-sig-mixed-models@r-project.org" <r-sig-mixed-models@r-project.org>
Enviado: domingo 24 de julio de 2011 19:06
Asunto: Re: [R-sig-ME] Cholmod warning


ote:

> Dear list:

> I am implementing a model with lmer in which the dependent variable is the number \
> of chicks fledged by a number of barn swallow couples. I am using the \
> simplification method, and have realized that the order in which different elements \
> are introduced in the model has a great important, to the extent of making a "false \
> convergence" warning message disappear. After doing all the simplification, I \
> arrive to this model:

> s.hatchcoltailmodel1.76<-lmer(nhatch1~sex+tlength+brithr+briventral+cond+weatherpc1+ \
> weatherpc1:briventral+weatherpc1:cond+(1|site/pair)+(1|year),family=poisson,na.action=na.omit)
> 

> This one, the LAST one (and the simplest) gives me this error message:

> Mensajes de aviso perdidos
> 1: In mer_finalize(ans) :
> Cholmod warning 'not positive definite' at file:../Cholesky/t_cholmod_rowfac.c, \
>                 line 432
> 2: In mer_finalize(ans) :
> Cholmod warning 'not positive definite' at file:../Cholesky/t_cholmod_rowfac.c, \
>                 line 432
> 3: In mer_finalize(ans) : false convergence (8)

> No matter the order in which I write the elements.

> I really cannot understand how it is possible that I have been able to make all the \
> simplification from the maximal model (18 parameters), and after a long and careful \
> process, exactly when I arrive to my minimal model (8 parameters and only 2 \
> interactions) is when everything collapses. It is really annoying.

Add the verbose=TRUE option to see if you can determine which of the
parameters is going off to unusual values.  It is entirely possible
that your model is overparameterized.

> 
> Any suggestions, comments or ideas'll be much appreciated.
> 
> Thank you very much.
> 
> 
> ________________________________________
> 
> Iker Vaquero-Alba
> Centre for Ecology and Conservation
> Daphne du Maurier Building
> University of Exeter, Cornwall Campus
> Treliever Road
> TR10 9EZ Penryn
> U.K.
> 
> http://biosciences.exeter.ac.uk/cec/staff/postgradresearch/ikervaquero-alba/
> [[alternative HTML version deleted]]
> 
> 
> _______________________________________________
> R-sig-mixed-models@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
> 
> 
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