Modified Double Sampling Control Chart for Monitoring the Coefficient of Variation

Abstract

Monitoring the coefficient of variation (CV) has received wide attention in quality control, mainly used when the process mean and standard deviation are not constant. This work proposes a modified Double Sampling (DS) chart for monitoring the CV, denoted DS-G chart, in order to improve the sensitivity of previous DS chart for monitoring the CV, denoted DS-γ chart. Some numerical results for statistical properties of the proposed chart and performance comparisons are provided in the form of tables. Based on the average number of observation to signal (ANOS) performance, the proposed DS-G chart outperforms the DS-γ chart.