Monitoring the process mean using a synthetic X¯ control chart with two sampling intervals

Article type: Research Article

Authors: Wan, Qiang^{a; *} | Zhu, Mei^b | Liu, Yan^a

Affiliations: [a] School of Business, Xinyang Normal University, Xinyang, China | [b] College of International Education, Xinyang Normal University, Xinyang, China

Correspondence: [*] Corresponding author. Qiang Wan, School of Business, Xinyang Normal University, Xinyang, China. E-mail: w77happy@xynu.edu.cn.

Abstract: The traditional fixed sampling interval (FSI) synthetic X¯ control chart is sensitive to large and moderate process shifts, but insensitive to small process shifts. This paper proposes an improved variable sampling interval (VSI) synthetic X¯ control chart with two sampling interval lengths for monitoring the process mean. A Markov chain method is used to compute the adjusted average time to signal (AATS) of the proposed chart. The statistical design of the VSI chart is then formulated and solved with a specific genetic algorithm. Comparisons are made to show the capability of the VSI chart in yielding average performance boost of 16.4%, in the AATS of the VSI chart scheme compared to the situation in which the corresponding FSI chart is used.

Keywords: Statistical process control, synthetic X control chart, variable sampling interval, adjusted average time to signal

DOI: 10.3233/JIFS-190600

Journal: Journal of Intelligent & Fuzzy Systems, vol. 38, no. 4, pp. 4191-4203, 2020