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Quasi-poisson glm and calculating a qAIC and qAICc...trying to modilfy Bolker et al. 2009 function to work for a glm model

3 messages · Gavin Simpson, Jason Nelson

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On Thu, 2011-01-27 at 08:20 -0500, Jason Nelson wrote:
You are out of luck there then; logLik is not defined for the quasi
families.
phi, IIRC, is the dispersion parameter. You can get the estimated value
from `summary(model)$dispersion` where model is the result of a call to
glm().
Instead of resorting to these ad-hoc approaches to correct for
overdispersion, you would be better off fitting models that model the
overdispersion. Try a negative binomial (glm.nb() in MASS) or the
zeroinfl() and hurdle() functions in the pscl package. Those all have
proper log likelihoods and you can compute/extract AIC simply using
them.
HTH

G