A comparison of the robustness of reliability growth assessment techniques

Reliability assessment techniques constitute an important element of the reliability growth program. This paper examines the accuracy and robustness of two widely used reliability growth assessment techniques under a number of realistic corrective action processes. These methods are also compared to a newly developed assessment approach. The new approach provides a more robust assessment across a broader spectrum of cases. These include various corrective action processes as well as cases in which the number of failure modes in the system is not large compared to the number of failure modes surfaced during testing. The results indicate that each of the techniques perform acceptably well under test conditions that adhere to the assumptions on which they are based. The performance can be severely degraded when the assumptions are violated, and this is the case with the Crow-Extended Model. The AMSAA Maturity Projection Model (AMPM) and the newly developed alternate technique have a somewhat limited number of assumptions though. They appear to be more robust to the various test conditions examined here, with the alternate being the most useful across the broadest spectrum of cases.