Could you help me to proceed with a request by a reviewer?
I have a Cox model like this
time_1year | status ~ p1 + p2 + p3 + p4
I was not able to perform Cox regression at 2 year as the proportional hazard assumption was violated.
Reviewer asked us to do the following:
Conduct an analysis that includes time x covariate interactions to address non-proportional hazards, so that mortality risk at 2 year can be assessed.
What and how should I do it? I can use R and SPSS.