Knowledge
Metrology Dictionary
The complete VIM vocabulary — all numbered concepts of JCGM 200:2012 as faithful paraphrases with clause citations — plus clearly labeled practice terms from the GUM, ILAC, ISO and NIST guidance.
Material measure
A device reproducing or supplying, in a permanent manner during its use, quantities of given values — gauge blocks, standard weights, volumetric flasks, standard resistors.
VIM (JCGM 200:2012) 3.6 · Instruments
Maximum permissible error (MPE)
The extreme value of measurement error, with respect to a known reference value, permitted by specifications or regulations for a given instrument. Verification confirms indications fall within ±MPE.
VIM (JCGM 200:2012) 4.26 · Instruments
Measurand
The quantity intended to be measured. Specifying a measurand requires the kind of quantity and a description of the state of the phenomenon, body, or substance carrying it.
VIM (JCGM 200:2012) 2.3 · General
Measured quantity value
The quantity value representing a measurement result — the value actually obtained for the measurand in a given measurement.
VIM (JCGM 200:2012) 2.10 · General
Measurement
The process of experimentally obtaining one or more quantity values that can reasonably be attributed to a quantity, presupposing a description of the quantity, a procedure, and calibrated equipment.
VIM (JCGM 200:2012) 2.1 · General
Measurement accuracy
Closeness of agreement between a measured value and a true value of the measurand. A qualitative concept — a measurement is more accurate when it offers smaller error, but accuracy itself is not a number.
VIM (JCGM 200:2012) 2.13 · General
Measurement bias
The estimate of a systematic measurement error — typically the difference between the mean of repeated indications and an accepted reference value.
VIM (JCGM 200:2012) 2.18 · Statistics
Measurement error
Measured quantity value minus a reference quantity value; comprises a systematic component and a random component.
VIM (JCGM 200:2012) 2.16 · General
Measurement function
The function whose output value, computed from the input quantity values, is the measured value of the output quantity — Y = f(X₁, …, Xₙ) when the model can be solved explicitly.
VIM (JCGM 200:2012) 2.49 · Uncertainty
Measurement method
A generic description of the logical organization of operations used in a measurement — substitution method, differential method, null method.
VIM (JCGM 200:2012) 2.5 · General
Measurement model
The mathematical relation among all quantities known to be involved in a measurement, of the general form f(Y, X₁, …, Xₙ) = 0.
VIM (JCGM 200:2012) 2.48 · Uncertainty
Measurement precision
Closeness of agreement between indications or measured values from replicate measurements under specified conditions — usually expressed as a standard deviation, variance, or coefficient of variation.
VIM (JCGM 200:2012) 2.15 · Statistics
Measurement principle
The phenomenon serving as the basis of a measurement — thermoelectric effect for a thermocouple, Doppler shift for a radar gun.
VIM (JCGM 200:2012) 2.4 · General
Measurement procedure
A detailed description of a measurement according to a principle and method, based on a measurement model — detailed enough that a trained operator can perform it. The SOP is its documented form.
VIM (JCGM 200:2012) 2.6 · General
Measurement repeatability
Measurement precision under repeatability conditions — the tightest, most flattering precision an instrument and operator can show.
VIM (JCGM 200:2012) 2.21 · Statistics
Measurement reproducibility
Measurement precision under reproducibility conditions — what interlaboratory comparisons quantify.
VIM (JCGM 200:2012) 2.25 · Statistics
Measurement result
The set of quantity values attributed to a measurand together with any other available relevant information — generally a measured value with its measurement uncertainty.
VIM (JCGM 200:2012) 2.9 · General
Measurement standard (etalon)
The realization of the definition of a given quantity, with stated value and uncertainty, used as a reference — an artifact, instrument, reference material, or measuring system.
VIM (JCGM 200:2012) 5.1 · Standards & Units
Measurement trueness
Closeness of agreement between the average of infinitely many replicate measured values and a reference value. Trueness relates inversely to systematic error, not random error.
VIM (JCGM 200:2012) 2.14 · Statistics
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.
VIM (JCGM 200:2012) 2.26 · Uncertainty
Measurement unit
A real scalar quantity, defined and adopted by convention, with which any other quantity of the same kind is compared to express the ratio of the two quantities as a number.
VIM (JCGM 200:2012) 1.9 · Standards & Units
Measuring chain
The series of elements of a measuring system constituting a single path of the measurement signal from sensor to output element.
VIM (JCGM 200:2012) 3.10 · Instruments
Measuring instrument
A device used for making measurements, alone or in conjunction with supplementary devices.
VIM (JCGM 200:2012) 3.1 · Instruments
Measuring interval
The set of values of quantities of the same kind that can be measured by a given instrument or system with specified instrumental uncertainty under defined conditions — the interval the specifications actually promise.
VIM (JCGM 200:2012) 4.7 · Instruments
Measuring system
One or more measuring instruments and often other devices, assembled and adapted to give measured values within specified intervals for quantities of specified kinds.
VIM (JCGM 200:2012) 3.2 · Instruments
Measuring transducer
A device, used in measurement, that provides an output quantity having a specified relation to the input quantity — a thermocouple, a load cell, a pressure-to-current converter.
VIM (JCGM 200:2012) 3.7 · Instruments
Metrological comparability of measurement results
Comparability of results traceable to the same reference — what shared traceability buys: results that can be meaningfully compared even from different labs and methods.
VIM (JCGM 200:2012) 2.46 · Calibration
Metrological compatibility of measurement results
The property of a set of results for a stated measurand such that the absolute difference of any pair is smaller than a chosen multiple of the standard uncertainty of that difference — the VIM's formal test for "do these results agree".
VIM (JCGM 200:2012) 2.47 · Statistics
Metrological traceability
The property of a result whereby it can be related to a stated reference — usually the SI — through a documented unbroken chain of calibrations, each contributing to the uncertainty.
VIM (JCGM 200:2012) 2.41 · Calibration
Metrological traceability chain
The sequence of standards and calibrations used to relate a result to a stated reference — the concrete path behind a traceability claim.
VIM (JCGM 200:2012) 2.42 · Calibration
Metrological traceability to a measurement unit
Traceability whose stated reference is the definition of a unit through its practical realization — "traceable to the SI" in its precise sense.
VIM (JCGM 200:2012) 2.43 · Calibration
Metrology
The science of measurement and its application — including all theoretical and practical aspects, whatever the uncertainty and field of application.
VIM (JCGM 200:2012) 2.2 · General
Multiple of a unit
A unit obtained by multiplying a given unit by an integer greater than one — the kilometre from the metre.
VIM (JCGM 200:2012) 1.17 · Standards & Units