Analysis of Performance-Degradation Data from Accelerated Tests

The performance of many products degrades as the product ages. Such degradation is usually slow but can be accelerated by a high `stress'. For example, the breakdown strength of electrical insulation depends on age and temperature. In some tests, the performance of a test unit is measured only once at a chosen age. For example, an insulation specimen yields only one breakdown measurement. A model and analyses for such data are described in this tutorial article. Also described is a method for estimating the distribution of time to failure, defined to be the age when performance degrades below a specified level.