[R-sig-ME] Dispersion parameter calculation for Poisson glmer; PS

[John Maindonald]

I do have a more cryptic response!  On most days, I do not believe that binomial
and poisson errors exist!

John Maindonald             email: john.maindonald at anu.edu.au
phone : +61 2 (6125)3473    fax  : +61 2(6125)5549
Centre for Mathematics & Its Applications, Room 1194,
John Dedman Mathematical Sciences Building (Building 27)
Australian National University, Canberra ACT 0200.
http://www.maths.anu.edu.au/~johnm

On 28/02/2013, at 9:57 AM, Douglas Bates <bates at stat.wisc.edu> wrote:

> On Wed, Feb 27, 2013 at 4:31 PM, Ben Bolker <bbolker at gmail.com> wrote:
> 
>> <juwb08 at ...> writes:
>> 
>>> 
>>> Hi All,
>>> 
>>> I would like to calculate a dispersion parameter for a glmer with a
>>> Poisson family (in lme4). I found a function posted on this mailing
>>> list that had been suggested to use for calculating a dispersion
>>> parameter for a glmer with a binomial family. (Found on
>>> https://stat.ethz.ch/pipermail/r-sig-mixed-models/2011q1/015383.html )
>>> 
>> 
>> [snip]
>> 
>>  Please see slightly more robust code at
>> 
>> http://glmm.wikidot.com/faq#overdispersion_est
>> 
>> It should be applicable to GLMMs generally, although please note all the
>> boldface warnings about this being a crude approximation of the
>> overdispersion parameter.
>> 
> 
> As you know, my opinion is that you can approximate it however you want
> because it doesn't exist :-)
> 
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> 
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