Dictionary · Uncertainty
Input quantity in a measurement model
A quantity that must be measured, or whose value can be otherwise obtained, to calculate a measured value of the measurand.
Related terms
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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
Output quantity in a measurement model
The quantity whose measured value is calculated from the input quantity values using the model — the measurand's seat in the mathematics.
VIM (JCGM 200:2012) 2.51
Triangular distribution
A probability distribution rising linearly to a peak midway between limits ±a. Used when values near the centre are more likely; its standard uncertainty is a/√6.
GUM (JCGM 100:2008) 4.3.9
Definitional uncertainty
The component of uncertainty resulting from the finite detail in the definition of the measurand itself — the floor below which no better procedure can go without redefining the quantity.
VIM (JCGM 200:2012) 2.27
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
Monte Carlo method (uncertainty)
Propagation of probability distributions through a measurement model by repeated random sampling, per JCGM 101:2008. Preferred when the model is strongly non-linear or distributions are non-normal.
JCGM 101:2008