A Comparison of Accelerated Life Test Plans for Weibull and Lognormal Distributions and Type I Censoring

Previous work on planning accelerated life test plans for the Weibull and lognormal distributions has concentrated on optimum test plans that minimize the variance of some specified estimator. However, these test plans use tests at only two levels of stress and, thus, have serious practical limitations. This article compares optimum test plans and some compromise test plans with respect to additional criteria including (a) the ability to detect departures from the assumed stress-life relationship and (b) robustness to departures from the assumptions used in determining the plans. The comparisons are based on the large sample properties of maximum likelihood estimators, and the test plans are compared over a range of practical testing situations. The comparisons suggest some general rules for planning accelerated life tests.