[R] binomial models with too many 1s???

[mike waters]

 I take it that a zero inflated negative binomial (i.e. Poisson) regression
model is what you are trying to fit, aka ZIP? If so try looking at the
documentation for the zicounts package for R, for one. Of course, you can
also search on these keywords yourself, to find exactly what you want....

Regards,

Mike

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of I.Szentirmai
Sent: 23 February 2006 17:24
To: R-help at stat.math.ethz.ch
Subject: [R] binomial models with too many 1s???

Dear R users,

Does anyone know a solution for the problem when there are too many ones or
zeros in the respons of a binomial model? 
I think this means that the data are over/under despersed and the result is
very bad model fit.

I'm using glmmPQL(family=quasibinomial) to fit a model to my data, but the
model estimates are not in the range they should be due to overdispersion
(or under?) What shall I do? Is there a model type for this kind of data? I
would prefer to keep all may data, otherwise I could also select some of the
ones so that their number will be equal to the number of zeros. But I don't
thik this is the right way...

Any help would be appreciated.

Thanks,
Istvan

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