Measurement uncertainty (MU)

A quantified parameter associated with a result that characterises the dispersion of values reasonably attributable to the measurand. Estimated by the GUM (Guide to the Expression of Uncertainty in Measurement) approach, combining Type A (statistical, from repeated measurement) and Type B (instrument calibration, environmental, reference-material) components, and reported as an expanded uncertainty U with coverage factor k = 2 for roughly 95 percent confidence.