[R-sig-ME] overdispersion estimation in a binomial GLMM
Thomas.Merkling at cict.fr
Thu Jan 20 16:59:18 CET 2011
Dear list members,
I am trying to fit a binomial GLMM and I wonder if there is
overdispersion. I'm not sure to know how to do it. I tried to fit with
"quasibinomial" family but apparently it doesn't exist anymore in lme4.
I also tried this but I am not sure that it is true for mixed models.
k <- attr(logLik(model),"df") #
n <- length(fitted(model))
pearsonresid <- (1/(n-k)) * sum(resid(model,"pearson")^2) # 1.731892
dev <- deviance(model)/(n-k) #2.378512
One more thing: how to deal with this model if there is overdispersion ?
Thanks by advance,
Thomas Merkling, Doctorant (PhD Student)
Laboratoire "Evolution et Diversité Biologique" -EDB
UMR 5174 - bât 4R3 b2 - bureau 226
Université Paul Sabatier Toulouse 3
118, route de Narbonne
31062 TOULOUSE Cedex O9, FRANCE
Tél: 33 5-61-55-67-58
Fax: 33 5-61-55-73-27
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