Planning step-stress life test with progressively type I group-censored exponential data

Accelerated life testing of products is used to get information quickly on their lifetime distributions. This paper discusses a k-stage step-stress accelerated life test under progressive type I censoring with grouped data. An exponential lifetime distribution with mean life that is a log-linear function of stress is considered. A cumulative exposure model is also assumed. We use the maximum likelihood method to obtain the estimators of the model parameters. The methods for obtaining the optimum test plan are investigated using the variance-optimality and D-optimality criteria. Some numerical studies are discussed to illustrate the proposed criteria.