title: A version of the EM algorithm for proportional hazard model with random effects.
abstract: Proportional hazard models with multivariate random effects (frailties) acting multiplicatively on the baseline hazard have recently become a topic of an intensive research. One of the main practical problems related to the models is the estimation of parameters. To this aim, several approaches based on the EM algorithm have been proposed. The major difference between these approaches is the method of the computation of conditional expectations required at the E-step. In this paper an alternative implementation of the EM algorithm is proposed, in which the expected values are computed with the use of the Laplace approximation. The method is computationally less demanding than the approaches developed previously. Its performance is assessed based on a simulation study and compared to a non-EM based estimation approach proposed by Ripatti and Palmgren (2000).
authors.affiliation: Center for Statistics, Limburgs Universitair Centrum, Universitaire Campus, B-3590 Diepenbeek, Belgium. jose.cortinas@luc.ac.be
authors.forename: José Cortiñas
authors.initials: JC
authors.lastname: Abrahantes
authors.forename: Tomasz
authors.initials: T
authors.lastname: Burzykowski
mesh_terms: D000465:Algorithms; D015982:Bias; D001943:Breast Neoplasms / Q000188:drug therapy / Q000601:surgery; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D009010:Monte Carlo Method; D015337:Multicenter Studies as Topic / Q000706:statistics & numerical data; D016016:Proportional Hazards Models; D012044:Regression Analysis; D016019:Survival Analysis