Design of adaptive s control charts |
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Authors: | Tsen-I Kuo Pei-Hsi Lee |
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Institution: | 1. Department of Business Administration, National Quemoy University, No. 1, University Road, Jinning Township, Kinmen 892, Taiwantikuo@nqu.edu.tw;3. Department of Business Administration, Chung Yuan Christian University, Chung Li, Taiwan |
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Abstract: | The Shewhart s chart has been widely used to monitor the standard deviation of a process. However, the main disadvantage of an s chart is its slowness to signal small increases in the variability. In this paper, ideas of adaptive control charts are extended to the Shewhart s chart for improving the efficiency in signalling increases in the standard deviation. A Markov chain model is applied to evaluate its performances and compares its performances with combined double sampling and variable sampling intervals s chart, variable parameters (VP) R chart, exponentially weighted moving average and Cusum charts. The statistical performances show that the VP s chart is more sensitive to increases in standard deviation. |
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Keywords: | Shewhart s control chart adaptive control charts statistical design Markov chain method chi-square distribution |
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