European and international standards for derivation and statements of uncertainties

Modern well-developed high technologies need “precise measurements” standing for high reproducibility in performance or operation of products and parts. Today´s strong national and international interconnections in trade and industry require traceability of measures. Traceability is the property of the result of a measurement whereby it can be related in a clear and well-defined way to appropriate standards, generally national or international ones, and by these to the conventional units through an unbroken chain of comparisons. This means that comparison of values is needed on nearly each level. In order to compare values, one needs a judgement on the reliability of those values, in short terms, a statement of quality. Such a statement will be based on scientific knowledge, i.e. based on objective facts which can be inspected, but as a judgement it is always subjective in nature. General acceptance of a judgement may be achieved, however, if the way how the statement has been generated becomes transparent, so that every one can redo and understand its details. It is the objective of this talk to compile some fundamental concepts and terms involved in setting up a quality statement in metrology