Survival Analysis

1. SurvivalAnalysis Assist. Prof. E. Çiğdem Kaspar, PhD.

2. Time-Dependent Data Time dependent data are common in medicine. Ex: • Many monitors in surgery ( a variety of cardiac and pulmonary measures) • Cardiac stress measures are time dependent data • Electroencephalograms • Many apidemiologic measures are time depending, including survival.

3. Time Series A large number of observations recorded through time on the same variable usually called a time series in statistics. Although taken literally, time-dependent data would include before and after observations and posttreatment follow-up; data sets such as these are not considered time series. Survival data sets often have fewer observations than a true time series. Time series focus on a process through time rather than on a specific event.

4. Survival Time • Survival Time: Observations of the time until the occurence of a particular event, Ex: Recovery, improvement death

5. Survival Time • The generic name for the time issurvival time, although it may be applied to the time ‘survived’from complete remission to relapse or progression as equally as tothe time from diagnosis to death. • If the event occurred in allindividuals, many methods of analysis would be applicable. However,it is usual that at the end of follow-up some of the individuals havenot had the event of interest, and thus their true time to event isunknown.

6. Survival Time • Further, survival data are rarely Normally distributed,but are skewed and comprise typically of many early events andrelatively few late ones. It is these features of the data that make thespecial methods called survival analysis necessary.