In this paper the statistical performance of a Variable Sampling Interval (VSI) R Exponentially Weighted Moving Average (EWMA) control chart designed to monitor the range R of samples extracted out from a normally distributed population is investigated. For the investigated chart, the sampling interval can assume two different values. A statistically optimal design strategy based on the average time to signal the occurrence of an out-of-control condition is presented and the statistical performance of the VSI R EWMA chart is assessed through a comparison with other control charts used to monitor the process dispersion. The obtained results show how the possibility of varying the sampling interval significantly improves the performance of the VSI R EWMA chart with respect to the corresponding static chart and how this kind of chart is particularly suitable when reduction in the process dispersion should be detected.

Evaluation of the statistical performance of a variable sampling interval R EWMA control chart

CELANO, GIOVANNI;FICHERA, Sergio
2006

Abstract

In this paper the statistical performance of a Variable Sampling Interval (VSI) R Exponentially Weighted Moving Average (EWMA) control chart designed to monitor the range R of samples extracted out from a normally distributed population is investigated. For the investigated chart, the sampling interval can assume two different values. A statistically optimal design strategy based on the average time to signal the occurrence of an out-of-control condition is presented and the statistical performance of the VSI R EWMA chart is assessed through a comparison with other control charts used to monitor the process dispersion. The obtained results show how the possibility of varying the sampling interval significantly improves the performance of the VSI R EWMA chart with respect to the corresponding static chart and how this kind of chart is particularly suitable when reduction in the process dispersion should be detected.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11769/8931
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