Hi Ben,
Thank you very much for all your help, so far. Nonetheless, there is still
something not working. If you could have a look at the following code, I
would highly appreciate it. It's about how to count convergence problems of
function glmer within a simulation. I tried to adapt your proposal to my
models, but something's not working, probably to me lack of knowledge of
functions like tryCatch and withCallingHandlers.
I try the following (where alldata is a list of different data frames):

options(warn=2)

warn<-rep(NA,1000)

estglmer<-vector('list',1)
names(estglmer)<-'conv'

for(i in 1:1000){
    # The data to be used
    dd<-alldata[[i]]

    # The model to be fitted (Y, Category, fallswinner & ncombat are
variables in data frame dd)

mod<-glmer(Y~Category+fallswinner+(1|id),offset=(log(ncombat)),nAGQ=50,family="poisson",data=dd)

    # Here, we want to extract possible error/warning messages, but this
does not work
    estglmer$conv[i]<-withCallingHandlers(tryCatch(mod,
                      error = function(e) {
                          warn[i] <<- paste("ERROR:",e$message)
                          NA_ans
                      }),
                      warning = function(w) {
                          warn[i] <<- w$message
                          invokeRestart("muffleWarning")
                      })
}


I'm thinking about the topic and I don't know if it’s useful to obtain the
warnings/errors, because I should  look at each error and then I should
decide what I can do.

I only want to inform about percentage of convergence of GLMM, that is the
converge is true or false.  I understand that a model is considered as not
convergent  either if the estimation process did not converge or if the
estimate or its standard error was not provided. For example, in some cases
the parameter can be estimated but the estimation process was unable to
provide a positive definite variance-covariance matrix of the parameters
(problems with Hessian), mainly due to the instability of the model.

Thank you very much in advance for your suggestions.

Martí


2012/10/23 Martí Casals <mcasals@aspb.cat>

> Thank you so much Ben!!
>
> Martí
>
>
> 2012/10/23 Ben Bolker <bbolker@gmail.com>
>
>> Martí Casals <mcasals@...> writes:
>>
>> >
>> > I’m working on the simulation results and I would like to know the
>> > convergence of the GLMM model. For example, if I want to obtain the
>> > converge in the glm case with R, I can extract:
>> >
>> > model1<-glm(................family=" ",data=)
>> >
>> > *model1$converged*
>> >
>> > [1] TRUE
>> >
>> > I don’t know if exist a similar function in the lme4 package (glmer ).
>> >
>>
>>   I think not.
>>   I believe the only way to do this (it may have been discussed before)
>> is to use options(warning=2) to promote warnings to errors, then to use
>> tryCatch() etc. to intercept the errors and store the information
>> somewhere.
>>
>> http://comments.gmane.org/gmane.comp.lang.r.lme4.devel/8691
>> https://stat.ethz.ch/pipermail/r-help/2012-February/302767.html
>>
>>   I've added a bit on this to http://glmm.wikidot.com/faq, since it's
>> not the first time it has come up ...
>>
>>  Ben Bolker
>>
>> _______________________________________________
>> R-sig-mixed-models@r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
>>
>
>
>
> --
> Martí Casals Toquero
>
> Centre d' Investigació Biomèdica d'Epidemiología i Salut Pública
>
> Agència de Salut Pública de Barcelona
>
> Servei d' Epidemiologia
>
> Tel. 932384545 extensió: 391
>
> mcasals@aspb.es
>



-- 
Martí Casals Toquero

Centre d' Investigació Biomèdica d'Epidemiología i Salut Pública

Agència de Salut Pública de Barcelona

Servei d' Epidemiologia

Tel. 932384545 extensió: 391

mcasals@aspb.es

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