Dependence bias in conventional p-charts and its correction with an approximate lot quality distribution |
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| Authors: | Z Seyda Deligonul A Erhan Mergen |
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| Institution: | 1. Department of Management , Middle East Technical University , 1Associate ProfessorAnkara;2. Department of Decision Sciences , Rochester Institute of Technology , 2Assistant Professor, Rochester , NY , 14623 |
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| Abstract: | In this study, the variance of mean fraction nonconformance under the exact lot quality distribution with first order dependence is examined. The extent of the validity of binomial assumption with respect to the exact distribution in constructing the p-charts for dependent production processes is investigated and it is shown that neglect of dependence for small lot sizes may cause bias in the width of the area between the control limits. An approximate lot quality distribution with great versatility is proposed and is used for correcting the bias due to dependence in p-charts. |
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