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2. Measurement Process Characterization
2.2. Statistical control of a measurement process
2.2.3. How is short-term variability controlled?

Remedial actions

Examine possible causes A. Causes that do not warrant corrective action (but which do require that the current measurement be discarded) are:
  1. Chance failure where the precision is actually in control
  2. Glitch in setting up or operating the measurement process
  3. Error in recording of data

B. Changes in instrument performance can be due to:

  1. Degradation in electronics or mechanical components
  2. Changes in environmental conditions
  3. Effect of a new or inexperienced operator
Repeat measurements Repeat the measurement sequence to establish whether or not the out-of-control signal was simply a chance occurrence, glitch, or whether it flagged a permanent change or trend in the process.
Assign new value to test item With high precision processes, for which the uncertainty must be guaranteed, new values should be assigned to the test items based on new measurement data.
Check for degradation Examine the patterns of recent standard deviations. If the process is gradually drifting out of control because of degradation in instrumentation or artifacts, instruments may need to be repaired or replaced.
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