Oddsratio statement in proc logistic switching my reference group?

[fetterbug]

Hey there,

I am using the following code to test an interaction with PROC LOGISTIC:

proc logistic data=aim1;

     class group (param=ref ref='Usual_Care') surveycomp (param=ref ref='No');

     model init1stapp (event='Yes')= group surveycomp group*surveycomp/expb lackfit;

     oddsratio surveycomp;

run;

When the Wald Odds Ratio table is produced, the reference group for surveycomp = "Yes".

surveycomp No vs Yes at group=Intervention	0.349	0.228	0.535
surveycomp No vs Yes at group=Usual_Care	0.508	0.333	0.776

I'd prefer the reference group be the same as in the class statement (surveycomp = "No"). Is there a way to specify this in the ODDSRATIO statement?

Thanks so much!

-J

[Reeza · Accepted solution]

Use the DIFF option for the odds ratio statement.

oddsratio surveycomp/diff=ref;

[fetterbug]

Thank you! That worked like a charm.