Posterior distribution for negative binomial parameter pp using a group invariant prior

We obtain a noninformative prior measure for the pp parameter of the negative binomial distribution by use of a group theoretic method. Heretofore, group theoretic inference methods have not been applicable in the case of discrete distributions. A linear representation of a group leads to quantities whose squared moduli constitute the probability distribution. The group invariant measure yields prior measure dp/p2dp/p2.