[R] lmer - error asMethod(object) : matrix is not symmetric

[Douglas Bates]

This is similar to another question on the list today.

On Tue, Feb 16, 2010 at 4:39 AM, Luisa Carvalheiro
<lgcarvalheiro at gmail.com> wrote:
> Dear R users,
>
> I  am having problems using package lme4.
>
> I am trying to analyse the effect of a continuous variable (Dist_NV)
> on a count data response variable (SR_SUN) using Poisson error
> distribution. However, when I run the model:
>
> summary(lmer((SR_SUN)~Dist_NV + (1|factor(Farm_code)) ,
> family=poisson, REML=FALSE))
>
> 1 error message and 1 warning message show up:
>
> in asMethod(object) : matrix is not symmetric [1,2]
> In addition: Warning message:
> In mer_finalize(ans) : singular convergence (7)

So the first thing to do is to include the optional argument verbose =
TRUE in the call to lmer.  (Also, REML = FALSE is ignored for
Generalized Linear Mixed Models and can be omitted. although there is
no harm in including it.)

You need to know where the optimizer is taking the parameter values
before you can decide why.

P.S. Questions like this will probably be more readily answered on the
R-SIG-Mixed-Models mailing list.

> A model including  Dist_NV together with other variables runs with no problems.
> What am I doing wrong?
>
> Thank you,
>
> Luisa
>
>
> --
> Luisa Carvalheiro, PhD
> Southern African Biodiversity Institute, Kirstenbosch Research Center, Claremont
> & University of Pretoria
> Postal address - SAWC Pbag X3015 Hoedspruit 1380, South Africa
> telephone - +27 (0) 790250944
> Carvalheiro at sanbi.org
> lgcarvalheiro at gmail.com
>
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