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Verifying Measurement Uncertainty Using a Control Chart With Dynamic Control Limits

Published

Author(s)

Jun-Feng Song, Theodore V. Vorburger

Abstract

We propose a control chart with dynamic control limits that promotes the process of developing and refining an uncertainty budget and verifying the measurement uncertainty. The upper and lower dynamic control limits, µ +2s and µ - 2s, are calculated from an updated mean, µ, and standard deviation, s, using the measurement history for a check standard. The dynamic control limits are compared with the upper and lower fixed control limits, y + CL and y - CL, where y represents the reference value of the check standard; and CL represent the fixed control limit which is calculated from the specific, mostly random, components of the uncertainty budget of the calibration and the check standard. Only the uncertainty components that affect the variation of repeated measurements of the check standard are used to calculate the fixed control limits. If the dynamic control limits are close to the fixed control limits, it indicates that the measurement reproducibility for the check standard supports the estimated specific components of the uncertainty budget. Otherwise, these uncertainty components may be either over- or under-estimated, and they may need to be revised.
Citation
Measure: The Journal of Measurement Science
Volume
2

Keywords

check standard, control chart, control limit, measurement quality control, measurement uncertainty, uncertainty budget

Citation

Song, J. and Vorburger, T. (2007), Verifying Measurement Uncertainty Using a Control Chart With Dynamic Control Limits, Measure: The Journal of Measurement Science (Accessed October 1, 2023)
Created January 1, 2007, Updated February 19, 2017