Probability Plots for the Gamma Distribution

A procedure is presented for preparing probability plots for random samples from an assumed gamma distribution for any specified value of the shape parameter, η. Computational procedures for finding values of quantiles are developed, and tables of quantiles for a range of values of η0.1(0.1)0.6(0.2)5.0(0.5)10.0(1.0)20.0 and various precentage values are presented. Also a complete mechanization for the IBM 7090, from input to plot, is described. Various examples of gamma plots are presented to illustrate the characteristics of the procedure. A number of areas of application of gamma plotting in statistical analysis are discussed, with examples.