The result is generally acceptable.
Total Gage R&R is 1.9% of study variation and ndc is 74. Measurement variation is small relative to the selected part range. The asterisk matters: this five-part demonstration does not, by itself, approve the system for production use.
What supports “acceptable”
- Total GRR is below the common 10% guideline.
- Part-to-part variation clearly exceeds gage variation.
- ndc is well above the usual minimum of 5.
- The two operator means differ by only 0.0032 mm.
What still needs verification
- The five parts represent the actual process range.
- Measurement order was randomized.
- Operators used the normal production method.
- Resolution, calibration, fixture, and environment are adequate.
- %Tolerance is acceptable when specification-based decisions matter.
The study data
Every operator measures every part twice. Values are in millimetres.
| Part | Operator A · Trial 1 | Operator A · Trial 2 | Operator B · Trial 1 | Operator B · Trial 2 | Part mean |
|---|---|---|---|---|---|
| 1 | 10.018 | 10.021 | 10.024 | 10.020 | 10.02075 |
| 2 | 10.146 | 10.150 | 10.153 | 10.149 | 10.14950 |
| 3 | 10.278 | 10.274 | 10.281 | 10.276 | 10.27725 |
| 4 | 10.407 | 10.412 | 10.415 | 10.410 | 10.41100 |
| 5 | 10.536 | 10.532 | 10.541 | 10.537 | 10.53650 |
Why the result looks strong
The observed variation is overwhelmingly part-to-part. Repeatability is the larger measurement component, but it is still small beside the selected part range.
How to read the familiar %GRR guideline
Do not game the part range. A wider part range can reduce %Study Variation and inflate ndc. Select parts that represent the real process variation; when conformance to specifications matters, also review %Tolerance.
Calculation trail
| Component | Result | Interpretation |
|---|---|---|
| Equipment Variation (EV) | 0.019152 mm | Repeatability under the study conditions |
| Appraiser Variation (AV) | 0.009987 mm | Operator-to-operator component |
| Total Gage R&R | 0.021600 mm | Combined measurement variation |
| Part Variation (PV) | 1.139808 mm | Variation between selected parts |
| Total Variation (TV) | 1.140012 mm | Combined study variation |
For the complete Average & Range calculation sequence and constants, see the detailed calculation article.
Try the same study yourself
The free browser preview is preloaded with this dataset. Calculate it, change individual readings, and observe how repeatability, reproducibility, Total GRR, and ndc respond.
Bottom line
For this sample, yes: the measurement system appears capable of distinguishing the selected parts. For an actual approval decision, confirm the sampling, study execution, application risk, tolerance contribution, and required customer or company method. A good number is evidence—not a substitute for a valid study.