B1797
Title: Modelling the association structure in clustered right-censored survival data by factor copulas
Authors: Roel Braekers - Hasselt University (Belgium) [presenting]
Abstract: In clustered right-censored survival data, frailty and copula models are commonly used to describe the association between different lifetimes within the same cluster. We present a copula model based on factor copula functions to model the structure between the different event times. This new methodology allows the intracluster dependence to be flexibly modeled by any parametric family of bivariate copulas. In this way, we encompass a wide range of dependence structures. We establish three estimation procedures in this model: a one- and two-stage parametric method and a two-stage semiparametric method where marginal survival functions are estimated using a Cox proportional hazards model. For the parameter estimators, we prove that they are consistent and asymptotically normally distributed, and assess their finite sample behavior with simulation studies. Furthermore, we illustrate the proposed methods on a data set containing the time to the first insemination after calving in dairy cattle clustered in herds of different sizes.
