A Multiphase Software Reliability Model : From Testingto Operational

Accurate prediction of release times, reliability and availability of a software product requires the formulation of a reliability model which captures in a quantitative manner critical elements of the software testing process such as: (i) test coverage and (ii) the eeect of operational prooles. This paper presents a Non-Homogeneous Poisson Process(NHPP) based model which accounts explicitly for test coverage and can make predictions about the operational phase. The model provides, also, for defective fault detection and test coverage during testing and operational phases. The model yields reliability and availability functions which utilize test and operational data for making performance predictions during the operational phase. Stopping rules are developed for determining optimal software release times subject to various constraints such as cost, operational reliability and operational availability requirements.