Time-to-Event Data
death
DISEASE PROGRESSION, EVENT
Time-to-event data, such as time to disease progression and time to death, are frequently collected in the context of clinical trials. A special feature of time-to-event data is censoring, which occurs when the follow-up time is not long enough to observe the event of interest for all individuals or when individuals are lost to follow-up.To predict outcomes over the long term, censored time-to-event data usually need to be extrapolated beyond the observed follow-up period using a parametric survival model.The survivor function 
where The hazard function 
where Most cost-effectiveness models are in discrete time and therefore evaluate 