Optimum Step-Stress Accelerated Life Test Plan for Lomax Distribution with an Adaptive Type-II Progressive Hybrid Censoring

Abstract

The adaptive type -II progressive hybrid censoring has the advantage of saving both t he total test time and the cost of the experiment; also it increases the effi ciency of the statistical analysis. This article discuss es k-level step stress accelerated life tests based on an ad aptive type-II progressive hybrid censoring with product ' s life time following Lomax distribution. The scale param eter of the Lomax failure time distribution at constant levels is assumed to be a log line ar function of the stress level. Maximum likelihood estimators of the model parameters are derive d. Based on normal approximation to the asymptotic distribution of maximum likelihood estimators, t he approximate confidence intervals for model parameters are obtained. The optimal times of changing stress levels are discussed under Doptimality and A-optimality criteria. Such methods maximize the determinant and the trace of Fisher's information matrix for the model parameters. Analysis of t he numerical data has been presented for illustrative proposes.