A generalized statistical control chart for over- or under-dispersed data
Article first published online: 6 MAY 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Quality and Reliability Engineering International
Volume 28, Issue 1, pages 59–65, February 2012
How to Cite
Sellers, K. F. (2012), A generalized statistical control chart for over- or under-dispersed data. Qual. Reliab. Engng. Int., 28: 59–65. doi: 10.1002/qre.1215
- Issue published online: 18 JAN 2012
- Article first published online: 6 MAY 2011
- attribute control chart;
- Conway–Maxwell–Poisson distribution;
- count data;
- Poisson distribution;
- Shewhart control chart
The Poisson distribution is a popular distribution used to describe count information, from which control charts involving count data have been established. Several works recognize the need for a generalized control chart to allow for data over-dispersion; however, analogous arguments can also be made to account for potential under-dispersion. The Conway–Maxwell–Poisson (COM-Poisson) distribution is a general count distribution that relaxes the equi-dispersion assumption of the Poisson distribution, and in fact encompasses the special cases of the Poisson, geometric, and Bernoulli distributions. Accordingly, a flexible control chart is developed that encompasses the classical Shewart charts based on the Poisson, Bernoulli (or binomial), and geometric (or negative binomial) distributions. Copyright © 2011 John Wiley & Sons, Ltd.