[R-sig-ME] Over-dispersion and lmer

[Ben Bolker]

Ricardo Solar <rrsolar at ...> writes:

> 
> Guys;
> 
> Really thanks for your help!!! Always with lots of solutions!
> 
> Thanks
> 
> On 20 December 2011 15:59, mikhail matz <matz at ...> wrote:
> 
> > Hey Ricardo -
> >
> > I faced this problem myself very recently, and there is a recent exchange
> > on the subject which seems to be an easy solution. Look up
> > R-sig-mixed-models Digest, Vol 47, Issue 53; thread by David Stainbrook.
> > Briefly, you can effect modeling with negative binomial distribution (which
> > takes care of the overdispersion) on counts data by using lognormal poisson
> > distribution.

 [snip]

>  There is even a reference to a paper laying
> > down the theory: Elston et al, Parasitology (2001), 122, 563-569.


  See also http://glmm.wikidot.com/faq , the section on overdispersion
(I tried to include a few more references there).
  Note that the lognormal-Poisson is *not* the same as the negative
binomial distribution, although it does have the same mean-variance
relation ...

  Ben Bolker