Hi All, I am working in the 'survival' library and need to know how to code a variable time interaction for left truncated data (not all subjects followed from the start of the study). I therefor add in the entry time and exit time variables into the formula.
Here is my basic formula CSHR.shore.fly <- coxph(Surv(entry, exit, to == 1) ~ shore.cat, data glba.mod) My variable shore.cat is violating the proportional hazards assumption so I am trying to add in an interaction with time. Do I interact exit? entry? or the range of the two? Thanks, Tim -- Tim Marcella 508.498.2989 timmarce...@gmail.com [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.