High Quality Content by WIKIPEDIA articles! In probability and statistics, the Yule Simon distribution is a discrete probability distribution named after Udny Yule and Herbert Simon. Simon originally called it the Yule distribution. This means that the tail of the Yule Simon distribution is a realization of Zipf's law: f(k; ) can be used to model, for example, the relative frequency of the kth most frequent word in a large collection of text, which according to Zipf's law is inversely proportional to a (typically small) power of k.