A control chart for the coefficient of variation

Chang W. Kang, Man S. Lee, Young J. Seong, Douglas M. Hawkins

Research output: Contribution to journalArticlepeer-review

146 Scopus citations


Monitoring variability is a vital part of modern statistical process control. The conventional Shewhart R and S charts address the setting where the in-control process readings have a constant variance. In some settings, however, it is the coefficient of variation, rather than the variance, that should be constant. For example, this setting is common in clinical chemistry, and then conventional R and S charts cannot be used. This paper develops a chart, equivalent to the S chart, for monitoring the coefficient of variation using rational groups of observations.

Original languageEnglish (US)
Pages (from-to)151-158
Number of pages8
JournalJournal of Quality Technology
Issue number2
StatePublished - 2007


  • Clinical chemistry
  • Process variability
  • Statistical process control


Dive into the research topics of 'A control chart for the coefficient of variation'. Together they form a unique fingerprint.

Cite this