A near‐optimal CUSUM‐CV chart

Abstract Monitoring of the process coefficient of variation (CV) with one‐sided CUSUM charts has been considered in the literature. In this short note, we develop a near‐optimal one‐sided CUSUM chart (with an explicit mathematical expression of the reference parameter) for detecting either increases or decreases in the CV of a normally distributed process. It is shown that the run‐length profiles of the existing and proposed one‐sided CUSUM‐CV charts (despite the fact that both charts possess different control‐charting structures) approximately remain the same. However, the proposed one‐sided CUSUM‐CV charts can be easily optimized when detecting a specific upward or downward shift in the in‐control process CV.