Deducing calibration and measurement capabilities from key comparisons

The Mutual Recognition Arrangement does not explain how the calibration and measurement capabilities of an institute should be deduced from the results of a key comparison. A way is proposed that uses the uncertainty budget of the measuring method and first identifies the main uncertainty contributions. Then, the results of the key comparison are used to support the main parts of the uncertainty budget of a participant. The uncertainty for a wide range of measurement conditions can then be calculated with this approved uncertainty budget. Additionally, the typical uncertainty budget of the method can help to choose the samples or measurement conditions for the comparison that allow checking the main uncertainty contributions independently. The ideas are illustrated by an example from density comparisons.