Incorporating inflection S-shaped fault reduction factor to enhance software reliability growth

Fault reduction factors (FRFs) play an important role in software reliability and are generally defined as the ratio of the total number of reduced faults to the total number of failures experienced. The behavior of FRFs is not fixed and can be affected by many factors, e.g., imperfect debugging, resource allocations, and debugging time lag. In most studies, either constant, increasing or decreasing FRFs have been considered. These are not sufficient to represent the realistic behavior of FRFs. We present three models in this study. In the first two models, an inflection S-shaped curve is considered as the FRF, and in the third model the FRF is constant. The first model functions in a perfect debugging environment whereas the second and third models function in an imperfect debugging environment. Here, the first two models are developed for single release software systems and the third is developed for multi-release software systems. Finally, a comparison is made with existing models in literature.