Re: GLM: CLASS and reference group

On Thu, 15 Sep 2005, Paul Thompson wrote:

(GLM referent group)
> > By virtue of the coding, I consider CLASS = "Z" to be the referent
> > group. Thus, may I consider each line above as a test of whether CLASS =
> > "X" and CLASS = "Y" are each statistically different from CLASS = "Z".
> > This seems painfully obvious, so I thought I'd take my chance to be a
> > pain
> >
> > If so, then by carefully naming the CLASS variables, I can adjust the
> > referent group? For instance, by changing "x" to "zX":
> >
>
> This is certainly true. Where are you going with this? Have you looked
> into contrasts, which allow you to simply test differences between
> groups, and are not dependent on the coding scheme?

Paul,

For now, I am only using it to break the rust. I think when I actually
get the data, there will be important covariates other than the
classification. For *this* scheme, the CONTRASTs have the *same*
results...

Many thanks,

Kevin

Kevin Viel
Department of Epidemiology
Rollins School of Public Health
Emory University
Atlanta, GA 30322