Mustofa Usman

Parametric Cox's Model for Partly Interval-Censored Data with Application to AIDS Studies

 Abstract—The Parametric Coxs Proportional Hazard Model based on Expectation-Maximization (EM) algorithm for partly interval-censored data is studied. We mean by partly interval-censored data that the observed data include both the exact and interval-censored observations on the survival time of interest. Through the simulation data and real data, we demonstrate that the resulting estimate of regression coefficient and its associated standard error. Our proposal is easily implemented by using SAS software in the present of partly interval-censored data.

Competing risks for reliability analysis using Cox's model

Purpose – Coxs model with Weibull distribution and Coxs with exponential distribution are the most important models in reliability analysis. This paper seeks to show that, with a large sample size based on expectation maximization (EM) algorithm, both models give similar results.Design/methodology/approach – The parameters of the models have been estimated by method of maximum likelihood based on EM algorithm. The objective of this analysis is to fit the modification of Coxs model with Weibull distribution and Coxs with exponential distribution, examine its performance and compare their results with Crowder et al.Findings – A simulation study indicates that the parametric Coxs model with Weibull distribution gives similar results to Coxs with exponential distribution, especially for a large sample size. Also, the modification of the two models showed better results compared with Crowder et al., especially for the second causes of failure.Originality/value – A modification of the two competing risk m...