Hi, I'm trying to fit a Cox regression model with age as the timescale, and I was wondering how you can check proportional hazards when this is the case, because the 'Assess option' doesn't work and my code to look at the Schoenfeld residuals isn't working either. I have code like this below: proc phreg data=data_set; class Drug (ref="None")/ desc; model (age_in, age_out)*no_deaths(0) = drug / rl; output out=test ressch=schres; run; proc sgplot data= test; loess x=(age_out-age_in) y=schres/clm; run; If I make a variable age_out-age_in before, then that is essentially the same as follow-up days, but I want to use age because I have a strong suspicion that the rates converge with older age. Should I really be checking if the drug violates the proportional hazards by follow-up time with an age at baseline interaction? Any help much appreciated. Thanks.
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