U-plot method for testing the goodness-of-fit of the power-law process

Abstract

This paper shows that the u plot method can be used as a statistical procedure for testing the fit of the Power-Law-Process (PLP), also called the Duane model. The u-plot was initially presented as a graphical tool for validating software reliability models. Mathematical derivations are given here to justify the use of u-plot as a statistical goodness-of-fit test for the PLP. These results give theoretical explanations to Downs and Scott sim¬ulation results. Methods and tools are suggested to further investigations which should lead to proving that the u-plot method can be considered as a common statistical goodness-of-fit test for several reliability growth mod¬els. The u-plot test is compared to classical PLP goodness-of-fit tests for different alternative models, and appears to perform very well.