Dear Eva;
I shouldn't have sent my unhelpful reply to the entire list, since it
is now glaringly obvious that I did not carefully read your original
question. You are outside my experience, since I have not used lme4,
but I wonder if questions about over-dispersion shouldn't be handled
by examining grouped residuals? According to the documentation, "mer"
models have a resid method, although the help page it links to appears
to be "under construction".
--
David Winsemius
Heritage Laboratories
On Oct 13, 2008, at 4:46 AM, Fucikova, Eva wrote:
Dear David,
Thank you for such a fast answer. Unortunatelly, your suggestion does
not work for lmer for some reason. I can probably try to run the model
without random effect to find out the overdispersion in the glm.
Anyway, thank you very much.
Yours sincerely,
Eva
-----Original Message-----
From: David Winsemius [mailto:[EMAIL PROTECTED]
Sent: maandag 13 oktober 2008 3:42
To: Fucikova, Eva
Cc: [email protected]
Subject: Re: [R] Overdispersion in the lmer models
Have you considered using glm() with family = "quasipoisson" or
family
= quasibinomial ? I know from experience that the quasipoisson choice
reports an index of dispersion.
?family
--
David Winsemius
On Oct 12, 2008, at 4:55 AM, Fucikova, Eva wrote:
Dear All,
I am working with linear mixed-effects models using the lme4 package
in R. I created a model using the lmer function including some main
effects, a three-way interaction and a random effect.
Because I work with a binomial and poisson distribution, I want to
know whether there is overdispersion in my data or not. Does anybody
know how I can retrieve this information from R?
Thank you in advance,
Eva Fucikova
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