Maximum Likelihood Estimation for Step-Stress Partially Accelerated Life Tests based on Censored Data

The aim of this article is to perform the estimation procedures on Rayleigh parameter in step-stress partially accelerated life tests (PALT) under both Type-I and Type-II censored samples in which all the test units are first run simultaneously under normal conditions for a pre-specified time, and the surviving units are then run under accelerated conditions until a predetermined censoring reached. It is assumed that the lifetime of the test units follows Rayleigh distribution. The maximum likelihood estimates are obtained for the proposed model parameters and acceleration factor for each of Type-I and TypeII censored data. In addition, the asymptotic variances and covariance matrix of the estimators are presented, and confidence intervals of the estimators are also given.