Parameter Estimation of the Beta-Binomial Distribution: An Application Using the Sas Software

Edson Zangiacomi Martinez, Jorge Alberto Achcar, Davi Casale Aragon


In this paper we describe the parameter estimation of the beta-binomial distribution using the procedure NLMIXED of the SAS software. The beta-binomial distribution is a discrete mixture distribution which can capture overdispersion in the data. The estimation of parameters of the beta-binomial distribution can lead to computational problems, since it does not belong to the exponential family and there are not explicit solutions for the maximum likelihood estimation. Using a real dataset, we show that the SAS software can be satisfactorily used for the estimation of the parameters. We also consider the possibility of including a covariate in the model. The SAS codes used in this paper are given in an Appendix.


beta-binomial distribution, regression model, data analysis


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