Proc GENMOD Class question

[fayez61]

Hello, 

I want to know if there is a way that I can elimnate refrence option in class statement using genmod procedure?

Because when I run my model, it gives me the last category of each variable in the class as a reference to that variable.

[RyanSimmons]

There are multiple ways to paramaterize class variables. You can change the paramaterization in the CLASS statement with the PARAM option. 

e.g.:

PROC GENMOD data=data;
     class treatment / param=X;
     model outcome = treatment;
run;

 where X is any of the options detailed here (e.g. ref, effect, glm, etc.). The default is the glm parameterization:

PROC GENMOD: CLASS Variable Parameterization

You can also use the REF option to specify the reference level.

e.g.: 

PROC GENMOD data=data;
     class treatment(ref='Control');
     model outcome = treatment;
run;