In R and Python, Cox regression is specified with
event as the dependent variables. However, Cox regression is said to be estimating the hazard ratio. How are the variables
event helping/assisting to estimate the hazard ratio, conceptually, in Cox regression? And if Cox regression is predicting the hazard ratio, how is it being used to also predict time to the event for each individual (especially in the case where you want to use concordance as a sort of performance measure)?
duration is a one of the dependent variables, can I use covariates such as the age of the person at the start and end of the study (or when they've dropped out or succumbed to the event)? I'm a little concerned here, in my case, since
duration is the difference between the age at the end minus age at the beginning and I'm using both as covariates. I'd like to keep both since we would like to see if people entering at a younger age will have better survivals (start age), and if older people will have better survival (end age).
An help is appreciated.