GRAPHICAL REPRESENTATION OF 2 MIXED-WEIBULL DISTRIBUTIONS

A variety of shapes of 2-Weibull mixtures on Weibull probability paper (WPP) are explored and classified into 6 types of Cdf curves (A - F). Types B - D represent Cdf's composed of 2 well-mixed subpopulations; type F represents the Cdf composed of 2 very well-separated subpopulations; and types A & E are in between types B - D and type F. The Kao-Cran graphical parameter estimation method can not be applied to type A - C, E, F curves; we recommend that it not be applied to the type D curve. The theoretical basis is developed for the Jensen-Petersen graphical method for mixtures with well separated subpopulations, viz, type F curve. For type A & E curves, the method can be applied. But for type B - D curves, there is no theoretical basis for the method.