Modeling the days of our lives: Using survival analysis when designing and analyzing longitudinal studies of duration and the timing of events.

Psychologists studying whether and when events occur face unique design and analytic difficulties. The fundamental problem is how to handle censored observations, the people for whom the target event does not occur before data collection ends. The methods of survival analysis overcome these difficulties and allow researchers to describe patterns of occurrence, compare these patterns among groups, and build statistical models of the risk of occurrence over time. This article presents a unified description of survival analysis that focuses on 2 topics: study design and data analysis