Covariance evaluation by means of uncertainty assessment

One of the key points in modern measurement science is the evaluation of measurement uncertainty, according to the definition given by the International Vocabulary of Metrology (VIM) [1] and the procedure recommended by the Guide to the Expression of Uncertainty in Measurement (GUM) and its supplements [2]-[4]. According to these documents, when several sources of uncertainty are present, the related standard uncertainties shall be quadratically combined, and the covariances must be considered, if present [2].