[R] Question on binomial data

[David Winsemius]

You should review your course material on interpreting general linear  
models. The criterion you have chosen for "significance" (looking at p  
values for indivdiual coefficients) is not the recommended one. Seek  
out the section that discusses the proper method for using deviance  
estimates for comparing nested models.

-- 
David Winsemius
On Apr 21, 2009, at 4:32 AM, ehud cohen wrote:

> Hi,
>
> We have an experiment with pass/fail outcome, and a continuous
> parameter which may contribute to the outcome.
>
> First, we've analyzed it by:
>
> p=c(F,T,F,F,F,T,T,T,T,T,T,T,F,T,T,T,T);
> w=c(53,67,59,59,53,89,72,56,65,63,62,58,59,72,61,68,63);
> l<-glm(p~w,family=binomial)
> summary(l)
>
> Which turned out to be non significant.
>
> Then, we thought of comparing the parameters of the two groups (passed
> vs. failed)
>
> t.test(w[which(p)],w[which(!p)],alternative="two.sided")
>
> which turned highly significant.
>
> I'd appreciate some insight...


David Winsemius, MD
Heritage Laboratories
West Hartford, CT