Unification of finite failure non-homogeneous Poisson process models through test coverage

A number of analytical software reliability models have been proposed for estimating the reliability growth of a software product. In this paper we present an Enhanced non-homogeneous Poisson process (ENHPP) model and show that previously reported Non-Homogeneous Poisson Process (NHPP) based models, with bounded mean value functions, are special cases of the ENHPP model. The ENHPP model differs from previous models in that it incorporates explicitly the time-varying test-coverage function in its analytical formulation, and provides for defective fault detection and test coverage during the testing and operational phases. The ENHPP model is validated using several available failure data sets.