Measurement system analysis (MSA) is an experimental and mathematical method of determining how much the variation within the measurement process contributes to overall process variability.
There are five parameters to investigate in an MSA: bias, linearity, stability, repeatability and reproducibility.
According to AIAG (2002), a general rule of thumb for measurement system acceptability is:
In addition to percent error and the number of distinct categories, you should also review graphical analyses over time to decide on the acceptability of a measurement system.
Automotive Industry Action Group (AIAG) (2002). Measurement Systems Analysis Reference Manual. Chrysler, Ford, General Motors Supplier Quality Requirements Task Force.