[R] How to increase iteration limit for lmer()?

[liujb]

Dieter,

Thank you very much for your reply.

I am sorry that I didn't provide data in my message. The data set is huge. 

Sorry for not specifying the model in the original message. It could be that
the problem is related to the model definition itself.
Here is my model:
x1_sq <- x1^2
x2_sq <- x2^2
lmer(y~x1 +x2 + x1_sq + x2_sq + t +(1+x1+x2+x1_sq+x2_sq|subject),
family=poisson)

In order to decrease the correlation between x1 and x1_sq, x2 and x2_sq, I
center the variables in the model. Of course, centering is not going to
remove collinearity completely. Could it be because of the collinearity
problem in the randomized variables.

Note, I tried the following models:
lmer(y~x1 +x2 + x1_sq + x2_sq + t +(1+x1+x2|subject), family=poisson)
lmer(y~x1 +x2 + x1_sq + x2_sq + t +(1+x1_sq+x2_sq|subject), family=poisson)

They all ran without any problem. 

And also, what is the syntax to increase iteration limit?

Thank you so much,
Julia


Dieter Menne wrote:
> 
> liujb <liujulia7 <at> yahoo.com> writes:
> 
>> I am running lmer(), and I had the following warning message:
>> "In mer_finalize(ans): iteration limit reached without convergence (9)
>> 
>> What is the default limit for lmer()? And how do I increase the limit?
> 
>>From what I know with lme (package nlme) where increasing the  limit is
possible
> with the control parameter, it never (for me) helped to increase the
> number of
> iterations. The message comes up when the case is ill-conditioned. Only
> verbose
> is a documented control parameter for lmer.
> 
> You should isolate your problem, and epost it to the lmer-list; but only
> do it
> if you can provide a full example with data, general questions on the
> subject
> will quite certainly go unnoticed. If you don't want to show your data,
> calling
> the variables x,y and z instead of income, tax, and voting is just fine.
> 
> lmer -list 
> 
> http://news.gmane.org/gmane.comp.lang.r.lme4.devel
> 
> 
> Dieter
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
> 

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