Uncertainty Modelling in Mass Comparisons

To evaluate uncertainty in mass measurements with accuracy and in accordance with recent international documents, a general model is developed, which takes account of the various contributing quantities in a multivariate context. On this basis, the variance-covariance matrix of the in-vacuo mass differences is constructed in its general form and tailored for application to some of the most commonly adopted weighing methods. The usual assumption of equal-variance, uncorrelated observations is shown to be inappropriate for mass comparisons.