Читать книгу Introduction to Statistical Process Control - Muhammad Amir Aslam - Страница 24

Yet another important probability distribution commonly used in the literature of the control charts for non‐normal random variables is the Gamma distribution. The probability distribution of the Gamma distribution can be defined as

with the scale parameter β > 0 and the shape parameter α > 0.

The mean and variance of the Gamma distribution are

and

respectively (Montgomery, 2009).