Chapter 9 Step-stress testing

In this chapter, step-stress models are considered as a particular form of accelerated life-test models. Under such models, under the assumption of cumulative exposure model, exact distributional forms of ordered lifetimes and exact distributions of maximum likelihood estimates are developed under various hybrid censoring schemes (including Type-I censoring, Type-II censoring, Type-I hybrid censoring, Type-II hybrid censoring and generalized hybrid censoring schemes). In particular, the case of exponential distribution is discussed in detail. As before, it is illustrated that B-spline functions can be used to represent the density functions of the maximum likelihood estimators.