The approaches for measurement uncertainty evaluation

Many important decisions are based on measurement. Result can be used for example to assess the conformity to statutory limits, to compare two methods... Whenever decisions are based on measurement, it is important to have some indication of the quality of the results. The uncertainty of measurement is the simplest way to express the reliability, of the results. Since the advent of the Guide to the expression of Uncertainty in Measurement (GUM) founding the principle of uncertainty evaluation, numerous projects have been carried out to develop alternate practical methods when it is impossible to model the measurement of the process for technical or economical aspect. These methods can use all the experimental data available for the laboratories, such as repeatability, reproducibility, quality control chart... The studies presented in this paper compare the results obtained by the modelling method from GUM with the uncertainty applying alternative methods.