Dictionary · Uncertainty
Measurement uncertainty
A non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used — the quantitative expression of doubt about a result.
Related terms
More from Uncertainty
Coverage probability
The probability that the set of true quantity values of a measurand is contained within a specified coverage interval — commonly 95 % in calibration practice.
VIM (JCGM 200:2012) 2.37
Standard measurement uncertainty
Measurement uncertainty expressed as a standard deviation, denoted u — the common currency into which all components are converted before combination.
VIM (JCGM 200:2012) 2.30
Welch–Satterthwaite formula
The formula for estimating the effective degrees of freedom of a combined standard uncertainty from the degrees of freedom of its components — used to select a coverage factor from the t-distribution.
GUM (JCGM 100:2008) G.4
Expanded measurement uncertainty
The product of a combined standard uncertainty and a coverage factor greater than one: U = k·u꜀. With k = 2 the coverage probability is about 95 % for a normal distribution.
VIM (JCGM 200:2012) 2.35
Type B evaluation of measurement uncertainty
Evaluation of a component of uncertainty by means other than statistical analysis of current measurements — calibration certificates, specifications, handbook data, assumed distributions.
VIM (JCGM 200:2012) 2.29
Coverage interval
The interval containing the set of true quantity values of a measurand with a stated probability, based on available information — unlike a classical confidence interval, not necessarily centred on the measured value.
VIM (JCGM 200:2012) 2.36