Optimized control charts using indifference regions

In statistical process monitoring, the CUSUM and EWMA control charts have received considerable attention because of their remarkable ability to detect small sustained shifts. practice, variation shifts are anticipated beforehand in many processes, so focus should be on detecting a moderate large shift. The aforementioned identify minor changes population parameters as out-of-control scenarios; thus, “small” potentially practically insignificant producing signals. To counteract this, both amended accommodate an indifference region by optimizing detection shift at outer boundaries region. results show that adapted monitoring schemes yield comparable results. On nearly all occasions, chart outperforms chart, yet seems more robust is easier interpret. Furthermore, we provide two practical examples illustrate use-case optimized mitigate (unimportant) variations, such seasonality modest temporary Overall, this work provides general approach tailored practice quality control, e.g., prescribed ISO standards. It also answers recent call literature reconsider design charts.