[R] GLM for proportional data

[Ben Bolker]

Mauricio Gomes <almeida.gomes <at> yahoo.com.br> writes:

> 
> 
> Dears,
> I'd like asking your help to understand a statistical issue 
> from my data set. I ran a GLM with proportional
> data, using a binomial distribution. However, 
> I've found underdispersion in my model and I don't
> know how to deal with that. I'm aware that a solution 
> for overdispersion is fit a model using a
> quasibinomial distribution, but I couldn't find in the l
> iterature a solution to my problem. I'd really
> thank if you can help me.
> Cheers,
> Mauricio

   This is really more of a statistical than a programming question,
but short answer: quasi-likelihood estimation (i.e. family=
quasibinomial) should address underdispersion and well as
overdispersion reasonably well.