## Quick Reference

A compound distribution that results from allowing the success probability in a sequence of Bernoulli trials to have a beta distribution. If the parameters of that distribution are *α* and *β*, then the probability of obtaining *r* successes in *n* trials is given by the beta-binomial distribution as where B is the beta function.

The distribution has mean *np* and variance, where .

*Subjects:*
Probability and Statistics.