Survival analysis is a collection of statistical procedures for data analysis, for which the
outcome variable of interest is time until an event occurs. It is the study of time between entry into
observation and a subsequent event. The term ‘Survival Analysis’ came into being from initial
studies, where the event of interest was death. Now the scope of the survival analysis has become
wide. Today scientists are using it for time until onset of disease, time until stock market crash, time
until equipment failure, time until earthquake, and so on. Common events studied are death,
disease, relapse, and recovery. Also, survival analysis is an important part of medical statistics,
frequently used to define prognostic indices for mortality or recurrence of a disease, and to study
the outcome of treatment.