Estimating a Dirichlet distribution Thomas P. Minka 2000 (revised 2003, 2009, 2012) Abstract The Dirichlet distribution and its compound variant, the Dirichlet-multinomial, are two of the most basic models for proportional data, such as the mix of vocabulary words in a text document. Yet the maximum-likelihood estimate of these distributions is not available in closed-form. This paper describes si