2. Interview the service provider laboratory (internal or external)

Any declaration of conformity or non-conformity is based on calibration results. However, all calibration results are subject to a calibration uncertainty which is often far from negligible compared to the MPE (maximum permissible error) of the instruments.

It is therefore essential to know the uncertainty with which the value measured on the instrument led to the declaration of non-conformity. When the laboratory is accredited by COFRAC, and the calibration is carried out under cover of accreditation (the COFRAC logo is then shown on the calibration document), the uncertainty announced is "certified" by COFRAC, but this does not mean that it is appropriate for the verification carried out. It is therefore necessary to find out, by questioning the laboratory, how it has been considered.

• The opinion is issued without...