Matching moments to phase distributions: Density function shapes

The authors study density-function shapes of distributions selected by phase-distribution-selection methods developed by Johnson and Taaffe. In one paper by Johnson and Taffe, analytic results for matching three moments to mixtures of two Erlang distributions of common order are presented. In another paper by Johnson and Taaffe; nonlinear programming methods are developed for matching three moments to mixtures of two Erlang distributions (not necessarily of the same order), real-parametered Coxian distributions with support on (0,•), and phase distributions with support on (0,•). In this paper, the authors investigate the effect of restricting selection to the above subsets of phase distributions. They also illustrate how to use the methods of Johnson and Taaffe to effect changes in density-function shapes.