I have a standard time to event data set, with both time-independent and time-varying covariates.
I assume the time to event is a discrete random variable, and construct the extended data set to estimate a logistic model (following this link: http://data.princeton.edu/wws509/notes/c7s6.html).
My questions are:
What is the independence assumption for the observations in the extended dataset?
My goal is the predict if $T_{i,t}$ will be an event for individual $i$ at time point $t$ with the trained logistic regression above. How should I split the extended dataset into training and testing set? Split by individuals or split by individual-time observations?