[R-sig-ME] about warning "In mer_finalize(ans) : singular convergence (7)"

[Douglas Bates]

On Thu, Feb 9, 2012 at 11:08 AM, Toni Hernandez-Matias
<ahmatias at gmail.com> wrote:
> Dear all,

> I am trying to fit a set of models with lmer function.
> My aim is to investigate the relationship between the abundance of a mammal
> species (count) and several environmental variables.
> The sample size is 648, but the observations are not independent and the
> random effect is nested: I have 10 study areas, within each area I
> performed 6 transects. I have 9-10 observations in all transects. So an
> example of a model with a single independent variable is:
> mod05<-lmer(cagaders~E_arb_alt+(1|ter)+(1|ter:trans),data=conill,family=poisson)

> When running this model I get the warning:
> In mer_finalize(ans) : singular convergence (7)

Try using verbose=TRUE to determine where the parameter values are
going during the iterative optimization process.

If your data could be made available, even in an anonymized form, we
could check the model fit against other optimizers that may be more
successful.

> I don't see an apparent reason for this warning.
> I would be very grateful if someone can help me to solve this problem and
> to know wether the results in the fitted model are credible.
>
> Thank you very much in advance,
>
> Toni
>
> --
> *********************************************************
>
> Antonio Hernandez Matias
>
> Departament de Biologia Animal (Vertebrats)
> Facultat de Biologia
> Universitat de Barcelona
> Av. Diagonal, 645
> Barcelona      08028
> Spain
> Telephone: +34-934035857
> FAX: +34-934035740
> e-mail: ahernandezmatias at ub.edu
>
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>
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