Frailty Models in Survival Analysis

The use of frailty models to account for unobserved individual he terogeneity and other random effects in survival analysis are discussed. After a description of proportional hazards models including random effects, the bio logical meaning of frailty and the res ulting problems for analys is are pointed out. The Survival Kit, a set of Fortran programs fo r the analysis of univariate frailty models has been developed by V. Ducrocq (Fr) and the author. Features of the Survival Kit are presented.