Local linear smoothing to estimate accelerated lifetime model with censoring and truncation

Abstract

A nonparametric accelerated failure time (AFT) model is considered to evaluate the dependability measures of a water supply system laid in a city of the Mediterranean Sea. To do it, a set of breakdown data of sections of pipe of the system is available. Unlike the usual methods that assume a parametric family for the underlying lifetime, we propose an AFT model with an unspecified distribution for the underlying lifetime. To carry out the model fitting we suggest a two-stage procedure. Firstly, we estimate the influence of certain factors over the lifetime of the system. Secondly, we propose modern and flexible statistical tools based on counting processes to construct a smooth estimate the reliability measure of a specific system. We prove the good asymptotic properties of the estimator.