PISMOEA
P.I.S.M.O.E.A. is an acronym that represents the sources of variation in a measurement system or Gage R&R study.
- Part – Production part, sample, measurand, Unit Under Test (UUT), artifact, check standard. Most of the variation should be coming from part-to-part or item-to-item variation, and little to no variation should be coming from the measurement system.
- Instrument – Gage, device, unit of Measurement and Test Equipment (M&TE), master gage, measuring machine, test stand. Examples include calipers, scoring matrix or rubric, risk assessment, meters, ruler, micrometer, photometer, power meter, thermometer, etc.
- Standard – Scale, reference, artifact, check standard, intrinsic standard, consensus, Standard Reference Materials (SRM), class, acceptance criteria
- Method – On-the-job training, verbal, work instruction, control plan, inspection plan, test program, part program
- Operator – Appraiser, calibration or test technician, assessor, inspector. You are trying to minimize any differences in measurements as a result of the person taking the measurements. Regardless of who does the assessment or takes the measurement, the decision should be the same.
- Environment – Temperature, humidity, contamination, housekeeping, lighting, position, vibration, power, Electromagnetic Interference (EMI), noise, time, air
- Assumptions – Statistical, operational, calibration, constants, handbook values, thermal stability, modulus of elasticity, laws of science. Examples include the assumption that the data comes from a normal distribution, that measurements are independent of each other (one result doesn’t influence another), that there is no wear on the part when taking multiple measurements, that operators are not aware of previous readings on the same part or influenced by other operators.
Examples of PISMOEA for three different measurement situations
PISMOEA was originally developed by Gordon Skattum, metrologist and Director of Integrated Manufacturing for Rock Valley College Technology Center.
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