Introduction to Survival Analysis Procedures

The LIFEREG procedure fits parametric accelerated failure time models to survival data that can be left-, right-, or interval-censored. The parametric model is of the form

where y is usually the log of the failure time variable, is a vector of covariate values, is a vector of unknown regression parameters, is an unknown scale parameter, and is an error term. The baseline distribution of the error term can be specified as one of several possible distributions, including (but not limited to) the log-normal, log-logistic, and Weibull distributions. Texts that discuss these parametric models include Kalbfleisch and Prentice (1980); Lawless (1982); Nelson (1990); Meeker and Escobar (1998). For more information about PROC LIFEREG, see Chapter 76, The LIFEREG Procedure.