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On Enhanced Interquartile Range Charting for Process Dispersion
Author(s) -
Riaz Muhammad
Publication year - 2015
Publication title -
quality and reliability engineering international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 62
eISSN - 1099-1638
pISSN - 0748-8017
DOI - 10.1002/qre.1598
Subject(s) - control chart , statistical process control , dispersion (optics) , range (aeronautics) , process (computing) , bivariate analysis , computer science , interquartile range , process control , statistics , set (abstract data type) , data mining , mathematics , engineering , optics , physics , operating system , programming language , aerospace engineering
A careful monitoring of process dispersion is necessary to get optimum output from any process. Control charts are very important process monitoring tools of Statistical Process Control toolkit. Interquartile range ( IQR ) is a famous dispersion measure that is used to monitor process dispersion in quality control literature. In this study, a set of auxiliary information‐based Shewhart‐type IQR charts are proposed for efficient monitoring of process dispersion under bivariate normal, t and gamma distributed processes. The control structures of the proposed charts are developed, and their performances are evaluated in terms of Average Time to Signal ( ATS ), Average Extra Quadratic Loss and Average Ratio to ATS . Comparisons are made among different charts to establish their superiorities for a quicker detection of process changes. An illustrative example is also provided to elaborate the procedural details of the proposed IQR charts using a real data set. Copyright © 2013 John Wiley & Sons, Ltd.