Journal of Integrative Natural Science (통합자연과학논문집)

The Basic Science Institute Chosun University (조선대학교 기초과학연구원)
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Multivariate EWMA Control Chart for Means of Multiple Quality Variableswith Two Sampling Intervals

  • Chang, Duk-Joon (Department of statistics, Changwon National University) ;
  • Heo, Sunyeong (Department of statistics, Changwon National University)
  • Received : 2012.06.08
  • Accepted : 2012.06.24
  • Published : 2012.09.30
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Abstract

Because of the equivalence between control chart procedures and hypothesis testing, we propose to use likelihood ratio test (LRT) statistic $Z_i^2$ as the multivariate control statistic for simultaneous monitoring means of the multivariate normal process. Properties and comparisons of the proposed control charts are explored and conducted for matched fixed sampling interval (FSI) and variable sampling interval (VSI) with two sampling interval charts. The result of numerical comparisons shows that EWMA chart with two sampling interval procedure is more efficient than the corresponding FSI chart for small or moderate changes. When large shift of the process has occurred, we also found that Shewhart chart is more efficient than EWMA chart.

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References

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