Proc hpgenselect with matched data

[Liamb]

Hello,

How to apply stepwise selection with proc hpgenselect to matched data?

Thanks

proc hpgenselect data=tab;
class paired var1 var2 var3 var4 ;
model wbc= var1 var2 var3 var4/ dist = negbin link=log ; 
/*random intercept / subject=paired;*/
selection method=stepwise details=all;

run;

[sbxkoenk]

Matched data? You mean data where treated units are matched to control units? Or you mean pre- and post- (treatment) measurements?

I am moving this topic to "Statistical Procedures" - board where it belongs.

Koen

[Liamb]

I mean data where treated units are matched to control units

[SteveDenham]

If you are locked into model selection techniques like stepwise, and you realize that it really isn't suited to mixed models, consider treating the difference between the treated and control subjects for each pair as your response variable. Without knowing your data structure, consider this:

proc hpgenselect data=tab;
class paired var1 var2 var3 var4 ;
model wbc_diff= var1 var2 var3 var4/ dist = negbin link=log ; 
selection method=stepwise details=all;
run;

The key here is in calculating the response variable wbc_diff. There are several ways, but all of them depend on the current structure of the dataset "tab".

You might be happier using method=lasso/choose=aicc, as it provides at lest some protection against type I error inflation due to multiple testing.

SteveDenham