4. Assessment of the Uncertainty in Analytical Results within the GUM Framework

The purpose of a measurement is to assign a value to the measurand, the quantity being measured.

The uncertainties inherent in any measurement process lead to an estimate of the value of the measurand—that is, to assigning the measurand the value in which we have the greatest confidence. As already mentioned, the variable “measurement result” can therefore be regarded as a random variable whose distribution can be summarized by two parameters:

• a measure of central tendency, which corresponds to the mathematical expectation of the distribution: this is the expected value;

• a measure of dispersion: the standard deviation of the distribution, also known as the standard uncertainty.

When it comes to evaluating the uncertainty of its measurements...