Optimal T2 Control Chart with a Double Sampling Scheme – An Alternative to the MEWMA Chart |
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| Authors: | Alireza Faraz Cédric Heuchenne Erwin Saniga |
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| Affiliation: | 1. Centre for Quantitative Methods and Operations Management, HEC Management School, University of Liège, , Liège, Belgium;2. Industrial Engineering Department, Islamic Azad University, , Iran;3. Department of Business Administration, University of Delaware, , Newark, Delaware, 19716 USA |
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| Abstract: | Recent studies have shown that a double sampling (DS) scheme yields improvements in detection times of process shifts over variable ratio sampling (VRS) methods that have been extensively studied in the literature. Additionally, a DS scheme is more practical than some of the VRS methods since the sampling interval is fixed. In this paper, we investigate the effect of double sampling on cost, a criterion as important as detection rate. We study economic statistical design of the DS T2 chart (ESD DS T2) so that designs are found that are economically optimal but yet meet desired statistical properties such as having low probabilities of false searches and high probabilities of rapid detection of process shifts. Through an illustrative example, we show that relatively large benefits can be achieved in a comparison with the classical T2 chart and the statistical DS T2 charts with our ESD DS T2 approach. Furthermore, the economic performance of the ESD DS T2 charts is favorably compared to the MEWMA and other VRS T2 control charts in the literature. Copyright © 2011 John Wiley & Sons, Ltd. |
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| Keywords: | Hotelling's T2 control chart MEWMA double sampling (DS) economic statistical design (ESD) genetic algorithm (GA) |
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