Proposal of a new distribution in PERT methodology

The aim of this paper is to present the generalized biparabolic distribution (GBP) as a good candidate to be utilized as the distribution underlying to PERT methodology (Malcolm et al., 1959). To do this and following the criteria established by Taha (1981) and Herrerías (1989), we will compare the mean and variance estimates derived from each proposed density function, viz beta, two-sided power (TSP) and GBP distributions. Also we will compare the estimates contributed by the mesokurtic and of constant variance families of the aforementioned distributions. The main conclusion is that the GBP distribution is the most convenient to be used in the PERT methodology because its mean is almost as moderate as that of trapezoidal and its variance is much higher than that of the rest of distributions. As a consequence, it can be stated that the GBP distribution is an alternative to the other four-parameter distributions.