Abstract
In this paper, how several existing software reliability growth models based on Non-homogeneous Poisson Processes (NHPPs) are derived based on a unified theory for NHPP models is described. Within this general framework, existing NHPP models are versified and new NHPP models are derived. The approach includes a number of known models under different conditions. Based on these approaches, a method of estimating and computing software reliability growth during operational phase is shown and using this method, the transitions from testing phase to operational phase is described. That is, a method for predicting the fault detection rate to reflect changes in the user’s operational environments is proposed. The proposed method offers a quantitative analysis on software failure behavior in field operation and provides useful feedback information to the development process.