08-05-2014 01:42 PM
Hi SAS experts and friends,
I'm trying to establish a fixed-effects model by using the new function Proc Panel.
My SAS code looks like this:
PROC PANEL DATA=mydata;
MODEL y=x1 x2 x3/FIXTWO VCOMP=WK;
ID pat_id year;
How can I assign a reference level to time variable (I don't want the last year as reference group) as well as to other covariates? I try to use PROC SORT & BY DESENDING time, however, PROC PANEL does not allow me to run the model (maybe because the time ordering is reversed). I also try to use CLASS time (ref="1999" param=ref) or ID year(1999) but still in vain.
Please help with this problem, many thanks!