[R-sig-ME] checking for overdispersion in lmer?

John Maindonald john.maindonald at anu.edu.au
Fri Aug 6 00:31:09 CEST 2010


The totals (input as weights if you are fitting proportions) need
to be supplied, with family=binomial.  You need to model the
extra variance, with observation level random effects.  If you
need an example, some of can supply one.  I gave an example
for overdispersed Poisson in a Dec 12 message last year.

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 05/08/2010, at 11:37 PM, touchtonj wrote:

> Hello,
> 
> How can I check for overdispersion in a lmer with proportion data? There is no residual deviance output like in a glm
> 
> thanks ~ janeene
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