Re: [R] GLMs: Negative Binomial family in R?

From: Pierre Kleiber <>
Date: Wed 06 Apr 2005 - 05:05:36 EST

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   Cheers, Pierre wrote:
> Greetings R Users!
> I have a data set of count responses for which I have made repeated observations
> on the experimental units (stream reaches) over two air photo dates, hence the
> mixed effect. I have been using Dr. Jim Lindsey's GLMM function found in his
> "repeated" measures package with the "poisson" family.
> My problem though is that I don't think the poisson distribution is the right
> one to discribe my data which is overdispersed; the variance is greater than
> the mean. I have read that the "negative binomial" regression models can
> account for some of the differences among observations by adding in a error
> term that independent of the the covariates.
> I haven't yet come across a mixed effects model that can use the "negative
> binomial" distribution.
> If any of you know of such a function - I will certainly look forward to hearing
> from you! Additionally, if any of you have insight on zero-inflated data, and
> testing for this, I'd be interested in your comments too. I'll post a summary
> of your responses to this list.
> Best Regards,
> Nadele Flynn, M.Sc. candidate.
> University of Alberta
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Pierre Kleiber, Ph.D       Email:
Fishery Biologist            Tel: 808 983-5399 / (hm)808 737-7544
NOAA Fisheries Service - Honolulu Laboratory    Fax: 808 983-2902
2570 Dole St., Honolulu, HI 96822-2396
  "God could have told Moses about galaxies and mitochondria and
   all.  But behold... It was good enough for government work."

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Received on Wed Apr 06 05:15:16 2005

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