1-for Determining Stability Obtain a sample and establish its reference value(s) relative to a traceable standard. If one is not available, select a production part that falls in the mid-range of the production measurements and designate it as the master sample for stability analysis. The known reference value is not required for tracking measurement system stability.
It may be desirable to have master samples for the low end, the high end, and the mid-range of the expected measurements.
Separate measurements and control charts are recommended for each.
2) On a periodic basis (daily, weekly), measure the master sample three to five times. The sample size and frequency should be based on knowledge of the measurement system. Factors could include how often recalibration or repair has been required, how frequently the measurement system is used, and how stressful the operating conditions are. The readings need to be taken at differing times to represent when the measurement system is actually being used. This will account for warm-up, ambient or other factors that may change during the day.
3) Plot the data on an X & R or X & s control chart in time order.
source of Determining Stability : Analysis of measurement systems
