Hoping for some help related to a survival analysis using R and the
survival package. I've been relying heavily on a series of blog posts done by Dayne Batten, particularly this portion:
I've collected and merged the data as instructed using the
tmerge function. My model relies on a cumulative time-dependent covariate, which strays away from the example provided. So my first question is does a cumulative covariate affect the validity of the Cox Regression? Here is my code at the moment:
fit <- coxph( Surv(tstart, tstop, had_event) ~ review_event, data = newdatatestcum)
My second question pertains to the lack of an ID being assigned within this model. For each customer ID within this data I have up to a few hundred lines of events with my covariate. I don't see how this regression could possibly be accounting for that.