A variable sampling interval run sum chart for the coefficient of variation
Document Type
Article
Publication Date
10-1-2022
Abstract
This paper proposes a variable sampling interval (VSI) run sum chart for the coefficient of variation (gamma), where the sampling interval is varied according to the current cumulative scores. Formulae to evaluate various performance measures for the proposed chart are derived, and algorithms to optimize the performance of the proposed chart using these measures are developed. These algorithms are then implemented on several numerical examples. Comparisons show that varying the sampling interval improves the performance of the run sum gamma chart. Furthermore, the VSI run sum gamma chart outperforms several existing charts in the literature. Implementation based on an illustrative example shows that the VSI run sum gamma chart reduces the time needed to detect an out-of-control signal compared with its fixed sampling interval (FSI) counterpart.
Keywords
Average Time to Signal, Control Charts, Coefficient of Variation, Run Sum, Variable Sampling Interval
Divisions
Science
Funders
Fundamental Research Grant Scheme [FP052-2018A],Research University Grant [GPF030B-2018]
Publication Title
Journal of Statistical Computation and Simulation
Volume
92
Issue
15
Publisher
Taylor & Francis
Publisher Location
2-4 PARK SQUARE, MILTON PARK, ABINGDON OR14 4RN, OXON, ENGLAND