|Measurement Systems Analysis
Measurement systems include variation and error, just like any other process. When a characteristic is measured the readings that are recorded include this measurement error.
It is easy to overlook this and assume that measurements reflect the true value of the characteristic. This can result in fruitless attempts to improve the process when the apparent variation is caused by variations in the measuring system. Measurement Systems Analysis should be an essential precursor to introducing Statistical Process Control, or using Design of Experiments
The variation of the measurement system is generally divided into repeatability error and reproducibility error, hence Gage R&R studies.
Errors that affect the accuracy of the measurement include bias, linearity and stability.
The system that establishes the relationship between a measuring device and a traceable reference standard. Calibration may include detecting, correlating, reporting or eliminating discrepancies in the accuracy of the measuring instrument.
A standard of known accuracy. The standard should be traceable to the national standard of the country concerned. In the United States that is the National Institute of Standards and Technology (www.nist.gov).
Gage Repeatability and Reproducibility. The combined effects of measuring systems repeatability and reproducibility:
The change in bias over the operating range of a measuring instrument.
See Measurement Systems Variation.
|Measurement Systems Capability
Short term estimate of the Measurement System Variation.
|Measurement Systems Variation
See Gage R&R
See Measurement Systems Analysis
See Number of Distinct Categories