Survival/Reliability

Survival/reliability analyzes the time until an event of interest occurs.

In survival analysis, the variable of interest is the time it takes until an event occurs. Time is the length of time in hours, days, months, weeks, years or some other unit. The event of interest is often death, recovery from surgery, product failure or some other characteristic. A key feature of survival analysis is that the event of interest may not occur during the study's time frame, or contact may be lost with the participant part way through the study. In these cases, the observation is said to be censored, and we only have partial but still important information about the survival time. Most survival data is right-censored because the true survival time has been cut off at the right side of the observed time, giving us an observed survival time shorter than the true survival time.

• Kaplan-Meier survival function
  The Kaplan-Meier estimator (also known as the product-limit estimator) is a non-parametric statistic used to estimate the empirical survival function.
• Proportional hazards fit
  A semi-parametric model that describes the relationship between a time to event response variable and one or more explanatory variables using a hazard function.