Optimal Step-stress Tests for Exponential Failure Data under Progressive Type-I Censoring

• Activity Number: 125
• Type: Contributed
• Date/Time: Monday, July 30, 2012 : 8:30 AM to 10:20 AM
• Sponsor: Section on Physical and Engineering Sciences
• Author(s): David Han*+ and Tony Ng
• Companies: The University of Texas at San Antonio and Southern Methodist University
• Keywords: accelerated life-testing ; cumulative exposure model ; Fisher information ; maximum likelihood estimation ; optimality criteria ; progressive Type-I censoring

Abstract

A k-step-stress accelerated life-testing is considered with an equal step duration. For small to moderate sample sizes, a practical modification is suggested in order to guarantee a feasible k-step-stress test under progressive Type-I censoring, and the optimal step duration is determined under this model. Next, we discuss the determination of optimal step duration under the condition that the step-stress test proceeds to the k-th stress level, and the efficiency of this conditional inference is compared to that of the previous case. In all cases considered, censoring is allowed at each point of stress change. The determination of optimal step duration is discussed under C-optimality, D-optimality, and A-optimality criteria. We investigate the case of progressively Type-I right censored data from an exponential distribution with a single stress variable.