Monitoring the Coefficient of Variation Using a Variable Sampling Interval Control Chart |
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| Authors: | Philippe Castagliola Ali Achouri Hassen Taleb Giovanni Celano Stelios Psarakis |
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| Affiliation: | 1. LUNAM Université, Université de Nantes & IRCCyN UMR CNRS 6597, , Nantes, France;2. Institut Supérieur de Gestion, Université de Tunis, , Tunis, Tunisia;3. Higher Institute of Business Administration of Gafsa, University of Gafsa, , Gafsa, Tunisia;4. Università di Catania, , Catania, Italy;5. Athens University of Economics and Business, , Athens, Greece |
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| Abstract: | The coefficient of variation (CV) is a quality characteristic that has several applications in applied statistics and is receiving increasing attention in quality control. Few papers have proposed control charts that monitor this normalized measure of dispersion. In this paper, an adaptive Shewhart control chart implementing a variable sampling interval (VSI) strategy is proposed to monitor the CV. Tables are provided for the statistical properties of the VSI CV chart, and a comparison is performed with a Fixed Sampling Rate Shewhart chart for the CV. An example illustrates the use of these charts on real data gathered from a casting process. Copyright © 2012 John Wiley & Sons, Ltd. |
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| Keywords: | coefficient of variation variable sampling interval average time to signal |
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