A Measurement System Evaluation (MSE) tells you whether your gauge or instrument can resolve the variation you are trying to study. Without a capable measurement system, every downstream analysis — capability, COV, DOE — is unreliable.
What an MSE measures
- Repeatability — variation when the same operator measures the same part repeatedly.
- Reproducibility — variation between operators measuring the same part.
- Stability — drift in the measurement system over time, visible on a control chart.
- Discrimination — the ratio of part-to-part variation to gauge variation; rule of thumb is ≥ 5 distinct categories.
Recommended workflow
- Select 8–10 parts that span the expected range of true values.
- Have 2–3 operators each measure every part 2–3 times in random order.
- Plot X̄ and R control charts by operator; the X̄ chart should be out of control (parts differ), the R chart in control (gauge is consistent).
- Compute the Gage R&R as a percent of total variation. <10% is excellent, 10–30% is acceptable for many uses, >30% means the system needs work before further analysis.
- Add an Individuals/MR chart over time using a single reference part to check long-term stability.
How Ops Excellence handles this
The MSE tool computes Gage R&R, renders both X̄/R and Individuals/MR control charts (X̄ above R, Individuals above MR), and reports the discrimination ratio alongside per-operator and per-part plots. Run an MSE on your own data.