05-01-2017 04:24 PM
I'm having an issue with a binary variable (location) coded 1/0 in a parametric Weibull survival model. For the main effect, only one level "hip" has a coefficient value since the other is a reference, but in the interaction term the same level "knee" is not being used as a reference. Thus in the interaction term both levels of the location variable are producing a coefficient. I highlighted the corresponding output in yellow. In other variables, such as race_num in this model, the main effect and interaction are working correctly. Can someone provide some insight about what is happening here?
Thanks for your help.
proc lifereg data = final ; class location gender revision bmi_cat race_num teaching; model new_time*event(0) = location race_num location*new_time race_num*new_time / dist=weibull; title "Model 7: Weibull Survival Model"; format location locationF. race_num raceF.; run;