Effect of measurement uncertainty on combined quality control charts

• Published in: Computers & industrial engineering Vol. 175; p. 108900
• Main Authors: Munir, Tahir, Hu, Xuelong, Kauppila, Osmo, Bergquist, Bjarne
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2023
• Subjects: Combined Control Chart; Kvalitetsteknik och logistik; Measurement Uncertainty; Monte Carlo Simulation; Multiple Measurements; Quality technology and logistics; Reliability Monitoring; Statistical Process Control; Multiple Measurements; Combined Control Chart; Reliability Monitoring; Measurement Uncertainty; Statistical Process Control; Monte Carlo Simulation
• ISSN: 0360-8352; 1879-0550; 1879-0550
• DOI: 10.1016/j.cie.2022.108900

•Measurement uncertainty has an adversarial effect on control chart performance.•This effect on combined control charts is studied through Monte Carlo simulations.•Multiple measurements at each sampling point can mitigate the effect.•Shewhart-Crosier’s CUSUM outperformed Shewhart-CUSUM in our study.•Shewhart-GWMA outperformed Shewhart-EWMA in our study. The accuracy of the measurement system is vital for reliable process monitoring using statistical process control charts. The applied chart’s effectiveness depends on the measurement system's performance. Measurement uncertainty can lead to incorrect decisions like unnecessary stops or failure to intervene. In this paper, we investigated the effect of measurement errors on the performance of four well-established combined charts for monitoring the mean of normally distributed processes: Shewhart-CUSUM, Shewhart-Crosier’s CUSUM, Shewhart-EWMA and Shewhart-GWMA charts. To deal with measurement errors we considered the additive measurement error model. Detailed run length profiles of these charts are studied in terms of average run length (ARL), extra quadratic loss, relative ARL, and performance comparison index through Monte Carlo simulations under different sizes of measurement errors. It was found that measurement errors significantly reduce the power of the combined charts. Thus, multiple measurements scheme is incorporated as a remedy to this effect. The Shewhart-Crosier’s CUSUM performed best of four charts, while the Shewhart-EWMA chart did worst. To demonstrate the effect of measurement uncertainty and highlight implications further, a simulated dataset with a shift in the process mean is considered.