A software reliability growth model considering an S-shaped testing effort function under imperfect debugging

Software testing effort and imperfect debugging are two important testing factors which can effectively improve the fitting and prediction power of a software reliability growth model (SRGM). Therefore, for describing the influence of these two factors on reliability in the modeling process more accurately, an S-shaped testing effort function (TEF) was proposed, which is also known as an inflected S-shaped TEF (IS-TEF). This function is suitable and flexible for describing the S-shaped varying trend of the testing effort's increasing rate. Then two new NHPP SRGMs (IS-TEFID1 and IS-TEFID2) were presented by incorporating IS-TEF and two forms of imperfect debugging into the exponential-type NHPP SRGM, respectively. Finally, on two real failure data-sets, a case study was proposed for comparing the two proposed models with several representative SRGMs in terms of fitting and prediction power. The experimental results indicate that compared with these SRGMs, the proposed IS-TEFID2 yields the best fitting and prediction results for each data-set. That is, incorporating IS-TEF and imperfect debugging into the NHPP SRGM can provide accurate fitting and prediction results.