Uncertainy of measurement and conformity assessment : a review

The uncertainty of measurement is the key indicator of the quality of any experimental result. A proper consideration of this parameter is imperative when testing a sample against legal/compositional limits. This task can be quite challenging when the entity measured in the investigated sample is so close to the limit that its uncertainty, anyhow estimated, critically affects decision-making. This explains the many literature contributions aimed to discuss the problem. Even if some of the most authoritative organisations issued specific guidelines aimed to assist the staff involved in such a kind of measurements, several aspects of conformity testing are still debated in the literature. In this review, after a short outline of the existing information, a somewhat more detailed insight is given to the guidelines of ASME, ISO and Eurachem/CITAC, since they represent the most useful tools for operators of testing and calibration laboratories. Some aspects of the Council Directive 96/23/EC are also commented. An insight into the contents of the mentioned documents allows highlighting analogies and discrepancies.