Survival analysis is a set of statistical methodologies used to analyze the occurrence of events over a period of time. When this analysis is applied to the biological science, death is the usual event. These analyses can also be applied to mechanical systems and measure the failures in these systems. When measuring these events, these models can be called time-to-event models.

This type of analysis is commonly used to evaluate treatment effects in clinical trials. One of the key questions that survival analysis tries to answer is this: what percent of the sample will live past a given time? Additionally, at what rate will the survivors die? One of the assumptions that this methodology is based upon is that death can occur only once per subject.

Issues Using Survival Analysis

Using this methodology, there are several issues that need to be contended with. Because these measurements often occur during a fixed period of time, not every subject has an event. Some subjects withdraw from the study prematurely while other subject live past the ending point of the study. When these conditions arise, the cases are called censored observations.

This analytical technique is being applied to more than just medical and mechanical trials. When considering using survival analysis in a research plan, you should consider having a statistical consultant review your design. This way you can address any methodological issues before they occur.