An S-shaped software reliability growth model with two types of errors

An S-shaped software reliability growth model (SRGM) based on a non-homogeneous Poisson process (NHPP) with two types of errors has been proposed. The errors have been classified depending upon their severity. We have estimated the model parameters and obtained the optimum release policies which minimize the cost subject to achieving a given level of reliability. Numerical results illustrating the applicability of the proposed model are also presented.