I'm pretty new to stats.. been working with cox models and getting a little confused.
1) Why do they occur? 2) How might one interpret/clinically translate a time-varying co-variate for cox models?
If an intervention itself is a a time-varying co-variate, what does this mean about the intervention? For example, if the betas drop over time (HRs increasingly favour control arm instead), can we say that there is "diminishing efficacy" of the treatment arm over time? Vice versa.
