Title: The sign chart with variable control and warning limits

Authors: Mohammed Kadhim Shanshool; Shashibhushan B. Mahadik; Ravindra E. Deore

Addresses: Department of Statistics, Shivaji University, Kolhapur, 416004, India ' Department of Statistics, Shivaji University, Kolhapur, 416004, India ' Department of Statistics, Shivaji University, Kolhapur, 416004, India

Abstract: Control charts with variable design parameters demonstrate improved statistical performance when compared to their counterparts with static design parameters. However, in case of some processes, the implementation of the charts with variable sampling interval and/or variable sample size can be complex because of the switches between sampling interval lengths and/or that between sample sizes. This paper proposes a sign chart for process location with variable control and warning limits (VCWL), whose implementation is just as simple as that of the static sign chart, and even so it demonstrates significantly better statistical performance than the later chart. The mechanism of the VCWL sign chart is illustrated through real-data examples.

Keywords: non-parametric control charts; adaptive control charts; average run length.

DOI: 10.1504/IJQET.2024.143747

International Journal of Quality Engineering and Technology, 2024 Vol.10 No.3, pp.213 - 225

Received: 01 Feb 2024
Accepted: 18 Jun 2024
Published online: 06 Jan 2025 *

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