[R] Weighted Logistic Regressions using svyglm

[tlumley at u.washington.edu]

On Mon, 19 Oct 2009, Fulton wrote:

>
> I’m running some logistic regressions and I’ve been trying to include weights
> in the equation.  However, when I run the model, I get this warning message:
>
> Here’s what it says:  Warning message: In eval(expr, envir, enclos) :
> non-integer #successes in a binomial glm!  
>
> I think it is because the weights are non-integer values.

Yes

> What is a good way to run logistic regressions in R when using non-integer
> weights?


You should use family=quasibinomial(). For svyglm() this is identical to binomial() except that it doesn't warn about non-integer weights.  

I'll update the documentation for svyglm() to make this explicit.

    -thomas

Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle