Each R&R study is evaluated according to the standard it is based on. The choice does not change the calculations, only the acceptance thresholds.
| Criteria | Standard | IATF 16949 |
| CPC — acceptable | > 4 | > 10 |
| CPC — limit | > 3 | > 3.33 |
| GRR % | < 25 % | < 10 % |
For the resolution, the standard reference is 5 % Tolerance (VDA) or 10 % (AIAG). For the NDC, the AIAG criterion is ndc ≥ 5, with the boundary zone ranging from 4 to 5.
⚠️ Select the standard before to draw a conclusion—not after seeing the results. A CPC of 6 is excellent under the Standard but insufficient under IATF 16949: it’s the same measurement, but not the same decision.