The uncertainty of a given measurement has equal importance to the reported measurement value.

Whilst this axiom is understood and applied by metrologists, advances in measurement techniques mean that the 'measurement value' now often results from:

• The outputs from a complex multi-input measurements system
• The processing of results using mathematical transforms - for example, DSP
• The output of mathematical models

All of these measurement outputs require an associated uncertainty to have useful meaning.

It is intended that the assessment of uncertainties for systems such as these are included as supplements to the Guide to the Expression of Uncertainty in Measurement (GUM), which is adopted internationally through standardisation bodies.

The NMS has a worldwide reputation in uncertainty evaluation which has been established through the support of the previous SSfM (now called Mathematics and Modelling for Metrology, MMM) programmes. This theme builds on this position and proposes work to develop and apply the GUM across the NMS and the international arena, including interlaboratory comparisons.