quasi-binomial family in lme4

Alas, I may have (in my own small way) contributed to this, by
including a quasi-Poisson example (of Arabidopsis fruiting) in a review
article in TREE.  We did look at the results reasonably carefully, and
they seemed to make sense in that case (although of course we didn't
know and still don't know what the 'true' answer is).  I should try to
re-run those analyses in various ways (primarily individual-level random
effects in glmer and MCMCglmm; the structure of the random effects is
currently too complicated for glmm.admb and gnlmm, I think ...)

-------- Original Message --------
Subject: Re: [R-sig-ME] quasi-binomial family in lme4
Date: Tue, 9 Nov 2010 15:02:45 +0000
From: Jarrod Hadfield <j.hadfield at ed.ac.uk>
To: T. Florian Jaeger <tiflo at csli.stanford.edu>
CC: r-sig-mixed-models at r-project.org

Hi Florian,

This comes up regularly and the list (nearly) always stays silent. As
far as I am aware quasi models in lmer do not, and never have, given
sensible results. To model over-dispersion you can try fitting an
observation-level random effect. For example:

data$resid<-as.factor(1:dim(data)[1])

and fitting (1|resid) in the model formula.

This year  I have reviewed four papers that have used quasi models in
lmer, and its no fun to tell the authors that their results may not be
meaningful. To paraphrase an earlier post, why are they there if they
do not work - it's irresponsible?

Jarrod

Hi,
I am analyzing some data that seems to require a quasibinomial model,
but the model returns incredibly small standard errors (and
correspondingly inflated t-values) that do not seem to be justified
given my data.
I've been reading (I think) all available posts on problems with the
quasi-binomial family in lme4. But I can't judge from the posts
whether all issues with the  quasi-binomial models in lme4 are assumed
to be resolved. So, I am wondering, are there any known issues with
quasi-binomial models in lme4?

I am using

Package:            lme4
Version:            0.999375-35
Date:               2010-08-18

in environment:
               _
platform       i386-pc-mingw32
arch           i386
os             mingw32
system         i386, mingw32
status
major          2
minor          11.1
year           2010
month          05
day            31
svn rev        52157
language       R
version.string R version 2.11.1 (2010-05-31)

cheers,
Florian

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