An Examination of the Robustness to Non Normality of the EWMA Control Charts for the Dispersion

The EWMA control chart is used to detect small shifts in a process. It has been shown that, for certain values of the smoothing parameter, the EWMA chart for the mean is robust to non normality. In this article, we examine the case of non normality in the EWMA charts for the dispersion. It is shown...

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Bibliographic Details
Published inCommunications in statistics. Simulation and computation Vol. 34; no. 4; pp. 1069 - 1079
Main Authors Maravelakis, Petros E., Panaretos, John, Psarakis, Stelios
Format Journal Article
LanguageEnglish
Published Colchester Taylor & Francis Group 01.10.2005
Taylor & Francis
Subjects
Applications
Average run length
Control charts
Exact sciences and technology
Exponentially weighted moving average control chart
Mathematics
Median run length
Non normality
Probability and statistics
Reliability, life testing, quality control
Sciences and techniques of general use
Statistical process control
Statistics
Control chart
Smoothing methods
Moving average
Median run length
Average run length
Estimator robustness
Median
Exponentially weighted moving average control chart
Statistical method
Statistical control
Non normality
Smoothing parameter
Control charts
EWMA mean chart
Statistical process control. 62N10
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Summary:The EWMA control chart is used to detect small shifts in a process. It has been shown that, for certain values of the smoothing parameter, the EWMA chart for the mean is robust to non normality. In this article, we examine the case of non normality in the EWMA charts for the dispersion. It is shown that we can have an EWMA chart for dispersion robust to non normality when non normality is not extreme.
ISSN:0361-0918
1532-4141
DOI:10.1080/03610910500308719