[R] overdispersion and quasibinomial model

[David Winsemius]

On Nov 24, 2009, at 3:41 PM, djpren wrote:

>
> I am looking for the correct commands to do the following things:
>
> 1. I have a binomial logistic regression model and i want to test for
> overdispersion.

Under the teach a man to fish precept,   ... try:

RSiteSearch("test over dispersion binomial models")

> 2. If I do indeed have overdispersion i need to then run a quasi- 
> binomial
> model, but I'm not sure of the command.

?glm
# and follow the appropriate links

> 3. I can get the residuals of the model, but i need to then apply a  
> shapiro
> wilk test to test them. Does anyone know the command for this?


RSiteSearch("shapiro-wilks")   # not that people here recommend this  
procedure

The overall flavor of these questions is "homework", so I'm  
speculating that you may want to consult your instructors.

-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT