Hello,

see http://glmm.wikidot.com/faq under 'How can I test for 
overdispersion?' and 'How can I fit a model that allows for 
overdispersion?'.  You might also want to check the mailing list 
archives, the overdispersion and quasipoisson issues have been debated a 
lot (and quasi was considered unreliable in lme4 and is not available 
since some time).

HTH

Cheers,
Luca







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Le 18/07/2012 17:47, Alejandro Martínez Abraín a écrit :
> Hi everyone,
>
> I have a couple of trivial questions.
>
> 1. How can I estimate overdispersion in a Poisson GLMMM?
>
> Is #lme4:::sigma(model) ok?
>
> Or does it make none sense to calculate overdispersion in a random model?
>
> 2. I am trying to run a quasipoisson GLMM using the lmer function and the
> lme4 library but I get a
> warning stating that "glmer cannot deal with quasi error families? Any tip?
> because I have seen this done.
>
> Thanks
> Alejandro
>
>
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