Methods for planning repeated measures accelerated degradation tests

Repeated measures accelerated degradation tests can sometimes be used to assess product or component reliability when one would expect few or even no failures during a study. Such tests can be used to estimate the lifetime distributions of highly reliable items. This paper describes methods for selecting a single‐variable accelerated repeated measures degradation test plan when the (possibly transformed) degradation that is linear in (possibly transformed) time and unit‐to‐unit variability is described by a random‐effects model. To find optimum test plans, we use a criterion based on a large‐sample approximation to the estimation precision of a quantile of the failure‐time distribution at use conditions. We also discuss how to find compromise test plans that satisfy practical constraints. We use the general equivalence theorem to verify that a test plan is globally optimum. The resulting optimized plans are also evaluated using simulation and compared with other test plans. Copyright © 2014 John Wiley & Sons, Ltd.