Weibull Prediction Intervals for Finite Lots When Testing Occurs at Stress Levels Other than Nominal,

摘要

In this paper a two-parameter Weibull model is assumed for time to failure (or number of cycles to failure). The inverse power law is assumed to relate level of stress and the Weibull scale parameter with the Weibull shape parameter independent of stress level. It is supposed that a life test results in Weibull failure-time data applying to the first r failures in a sample of size n. The procedure derived herein allows one to use these data to obtain an approximate lower confidence bound on the time of the i-th failure in a lot of size m selected from the same population as the sample. The precision of the approximation is investigated for certain cases in which i = 1, that is, the first failure in a lot is of interest. A method is given for determining whether the approximation is sufficiently precise for use, and an example of use of the approximation is provided. (Author)