On<tex>$q$</tex>-Logistic and Related Models

Abstract

Numerous types of asymmetrical distributions such as the logistic, Weibull, gamma, and beta distributions have been used for modeling various random phenomena such as those encountered in data engineering, pattern recognition, and reliability assessment studies. Several generalizations of the logistic distribution, and certain related models, are proposed in this paper. The corresponding density functions involve an additional parameter, denoted by q, which allows for increased flexibility for modeling purposes; in fact, the larger this parameter is, the lower the mode of the resulting distribution will be. Generalizations of the type-1 and type-2 beta distributions are introduced, along with their logistic-type counterparts; the moments and cumulants of the latter are also derived. Other extensions are discussed including a q-analog of the generalized type-2 beta model, a q-extended generalized logistic distribution, and q-analogs of generalizations of the Dirichlet distribution. As is shown graphically, the proposed univariate distributions can generate a wide array of unimodal or symmetric bimodal curves.