On a Six-parameter Generalized Logistic Distribution

Because of their flexibility, much attention has been given to the study of generalized models in recent times. In particular, many authors have investigated the properties of the generalized logistic distribution and its application in analysing bioassay and quantal response data. Recently, Wu Jong-Wuu et al (2000) developed a method which was used to obtain the density function of a five-parameter generalized logistic distribution. He investigated some of its properties and used it to analyse some bioassay data. In this present paper, we take a step forward by defining a suitable random variable that enables us to obtain a six-parameter generalized logistic distribution. The cumulants of the distribution are derived and it is indicated how an approximation to the c.d.f. can be obtained. Finally we state and prove some theorems that relate the distribution to some other common statistical distributions.