A Class of Life Distributions for Aging

Abstract

Abstract We introduce a new better than used of age t 0 (NBU-t 0) class of life distributions, where the survival probability at age 0 is greater than or equal to the conditional survival probability at specified age t 0 > 0. The dual class of new worse than used of age t 0 (NWU-t 0) life distributions is defined by reversing the direction of inequality. Preservation and nonpreservation properties of the two classes under various reliability operations are presented. We also show how to test, using a random sample, whether the NBU-t 0 class obtains.