[R-sig-ME] Beta-binomial distributions with lmer?
bolker at ufl.edu
Wed Jun 10 15:59:02 CEST 2009
That's a good question, answers will differ. Since "all models are
wrong" anyway, provided that a mean-variance relationship of V =
phi*N*p*(1-p) seems plausible, I would say you should go for it. You're
near the cutting edge anyway ... (I don't have a copy, but you might see
whether Zuur et al's book has anything to say on the subject -- they're
very pragmatic ecologists, and I think they use GEE/quasi models quite a
Christine Griffiths wrote:
> Thanks. I was hoping for a miracle that this had been developed within the
> last couple of months.
> I am on the stats learning curve and am not quite sure how flexible to be
> with regards to distributions. Is quasibinomial acceptable, despite having
> data with a lot of 0s and a lot of 100s?
> Many thanks in advance,
> --On 10 June 2009 09:18 -0400 Ben Bolker <bolker at ufl.edu> wrote:
>> No. You can use a quasi-binomial model, although
>> the support is a little bit spotty (and beware that
>> quasi- models may falsely report inflation of the
>> random effects).
>> Ben Bolker
>> Christine Griffiths wrote:
>>> Hi R users,
>>> Just a query as to whether lme4 can handle beta-binomial distributions
>>> as I read that this was not available.
>>> If not, any suggestions on how to handle such a distribution to plot the
>>> following model:
>>> y referring to percentage cover of biotic matter.
>>> R-sig-mixed-models at r-project.org mailing list
>> Ben Bolker
>> Associate professor, Biology Dep't, Univ. of Florida
>> bolker at ufl.edu / www.zoology.ufl.edu/bolker
>> GPG key: www.zoology.ufl.edu/bolker/benbolker-publickey.asc
> R-sig-mixed-models at r-project.org mailing list
Associate professor, Biology Dep't, Univ. of Florida
bolker at ufl.edu / www.zoology.ufl.edu/bolker
GPG key: www.zoology.ufl.edu/bolker/benbolker-publickey.asc
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