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Published on: July 24, 2013
An additive hazards frailty model with semi-varying coefficients
Zhongwen Zhang1, Xiaoguang Wang2, Yingwei Peng3
1School of Public Health and Management, Binzhou Medical University, Yantai, 264003, China.
Abstract:
Proportional hazards frailty models have been extensively investigated and used to analyze clustered and recurrent failure times data. However, the proportional hazards assumption in the models may not always hold in practice. In this paper, we propose an additive hazards frailty model with semi-varying coefficients, which allows some covariate effects to be time-invariant while other covariate effects to be time-varying. The time-varying and time-invariant regression coefficients are estimated by a set of estimating equations, whereas the frailty parameter is estimated by the moment method. The large sample properties of the proposed estimators are established. The finite sample performance of the estimators is examined by simulation studies. The proposed model and estimation are illustrated with an analysis of data from a rehospitalization study of colorectal cancer patients.
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