A control chart for monitoring process variation using multiple dependent state sampling

ABSTRACT

A control chart for monitoring process variation by using multiple dependent state (MDS) sampling is constructed in the present article. The operational formulas for in-control and out-of-control average run lengths (ARLs) are derived. Control constants are established by considering the target in-control ARL at a normal process. The extensive ARL tables are reported for various parameters and shifted values of process parameters. The performance of the proposed control chart has been evaluated with several existing charts in regard of ARLs, which empowered the presented chart and proved far better for timely detection of assignable causes. The application of the proposed concept is illustrated with a real-life industrial example and a simulation-based study to elaborate strength of the proposed chart over the existing concepts.

KEYWORDS:

• Average run length
• Control chart
• Multiple dependent state sampling
• process shift
• Variance

Acknowledgments

The authors are deeply thankful to the editor and reviewers for their valuable suggestions to improve the quality of this manuscript. The work by Muhammad Aslam was supported by fund of the Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah and also the work by Chi-Hyuck Jun was supported by a grant (#S0144-15-1007)from Gyungbuk Software Convergence Cluster Project funded by MSIT (Ministryof Science, ICT) and NIPA (National IT Industry Promotion Agency). The author, Muhammad Aslam, therefore, acknowledge with thanks DSR technical and financial support.