ABSTRACT
Survival analysis is a technique for investigating the effect of treatments or covariates on the first time to reach some important event. At any time, the hazard is the probability of the event occurring, given that it has not occurred so far. The survival function gives the fraction of the study sample for which the event has not occurred at each observation time. The survival function is easier to understand but the hazard function turns out to be easier to work with. The baseline hazard rate depends on time but ignores any treatment effects and covariates. Treatments or other covariates may affect the hazard rate, making the event less likely or more likely.
