Journal of Intelligent Manufacturing

, Volume 17, Issue 2, pp 243–250 | Cite as

The Updatable \(\overline{X}\) & S Control Charts

  • Z. Wu
  • M. Shamsuzzaman


The tools for Statistical Process Control (SPC) should be continuously improved in order to continuously improve the product quality. This article proposes a scenario for continuously improving the \(\overline {X}\) & S control charts during the use of the charts. It makes use of the information collected from the out-of-control cases in a manufacturing process to update the charting parameters (i.e. the sample size, sampling interval and control limits) step-by-step. Consequently, the resultant control charts (called the updatable charts) become more and more effective to detect the mean shift δ μ and standard deviation shift δ σ for the particular process. The updatable charts are able to considerably reduce the average value of the loss function due to the occurrences of the out-of-control cases. Noteworthily, unlike the designs of the economic control charts, the designs of the updatable charts only require limited number of specifications that can be easily decided.


Quality control Control chart Statistical process control Loss function Mean shift and variance shift 


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Copyright information

© Springer Science + Business Media, Inc. 2006

Authors and Affiliations

  1. 1.School of Mechanical and Aerospace EngineeringNanyang Technological UniversitySingapore

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