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http://dx.doi.org/10.7737/JKORMS.2014.39.1.001

Variable Sampling Interval $\bar{X}$ Control Chart Using Weighted Standard Deviation Method  

Chang, Youngsoon (Department of Business Administration, Myongji University)
Publication Information
Journal of the Korean Operations Research and Management Science Society / v.39, no.1, 2014 , pp. 1-12 More about this Journal
Abstract
This article proposes a variable sampling interval (VSI) $\bar{X}$ control chart using weighted standard deviation (WSD) method for skewed populations. The WSD method decomposes the standard deviation of a quality characteristic into upper and lower deviations and adjusts control limits and warning limits of a control chart in accordance with the direction and degree of skewness. A control chart constant is derived for estimating the standard deviation of skewed distributions with the mean of sample standard deviations. The proposed chart is compared with the conventional VSI $\bar{X}$ control chart under some skewed distributions. Simulation study shows that the proposed WSD VSI chart can control the in-control average time to signal (ATS) as an adequate level better than the conventional VSI chart, and the proposed chart can detect a decrease in the process mean of a quality characteristic following a positively skewed distribution more quickly than the standard VSI chart.
Keywords
Variable Sampling Interval; $\bar{X}$ Control Chart; Skewed Distribution; Weighted Standard Deviation;
Citations & Related Records
Times Cited By KSCI : 1  (Citation Analysis)
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