[R-sig-ME] false convergence glmer when quadratic terms are included

[Stijn Ruiter]

Dear all,
Somehow I always get false convergence warnings when including a
quadratic term in a glmer equation. With lmer I have no such problems.
So, my guess is that this has to do with the different algorithm used
for glmer models.
The following example model (which can easily be estimated in
alternative mixed effects programs such as MLwiN or HLM) result in problems:

glmer(y~(1|level2id)+x+I(x^2),family=binomial,data=data)

It leads to:
Warning message:
In mer_finalize(ans) : false convergence (8)

What is the problem here? Why these convergence issues?

Stijn

-- 
Best regards,

Stijn Ruiter
Department of Sociology / ICS
Radboud University Nijmegen
P.O. Box 9104
6500 HE Nijmegen
Netherlands

Phone: + 31 24 361 2272
Fax:   + 31 24 361 2399

Visiting address:
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Nijmegen

website: http://oase.uci.ru.nl/~sruiter