Beta Distribution

This chapter covers special cases and enhancements of the beta distribution. The beta-IV distribution or beta subjective distribution is identical to the beta-I distribution except that it incorporates the range of x in the PDF. The beta-IV can also be known as the PERT distribution, arising from its use with PERT project planning charts. The distribution relies on the three point estimation technique. The beta rectangular distribution is a mixture of the beta-I and uniform distributions. While the distribution is unlikely to be applicable, it does demonstrate the principle of combining distributions. Related to the beta-I distribution is the Kumaraswamy distribution. The chapter shows feasible values for skewness and kurtosis. Like beta-I, the Kumaraswamy distribution is one of the few that can exhibit both positive and negative skewness.