Yule–Simon distribution
（重定向自Yule distribution）
![](/Images/godic/202502/21/Yule-Simon_distribution_PMF.svg3930.png")
![](/Images/godic/202502/21/Yule-Simon_distribution_CMF.svg3930.png")
![Plot of the Yule–Simon(1) distribution (red) and its asymptotic Zipf's law (blue)](/Images/godic/202502/21/Yule-Simon_distribution3931.png")
In probability and statistics, the Yule–Simon distribution is a discrete probability distribution named after Udny Yule and Herbert A. Simon. Simon originally called it the Yule distribution.
The probability mass function (pmf) of the Yule–Simon (ρ) distribution is