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.
ITS-90
The International Temperature Scale of 1990: defined fixed points (e.g. the triple point of water, 273.16 K) and specified interpolation instruments through which practical temperature measurement is realized worldwide.
CCT / BIPM · Temperature
Indicating measuring instrument
A measuring instrument providing an output signal carrying information about the value of the quantity being measured — voltmeters, thermometers, balances.
VIM (JCGM 200:2012) 3.3 · Instruments
Indication
The quantity value provided by a measuring instrument or system — the reading, before any correction.
VIM (JCGM 200:2012) 4.1 · Instruments
Indication interval
The set of quantity values bounded by the extreme possible indications.
VIM (JCGM 200:2012) 4.3 · Instruments
Influence quantity
A quantity that, in a direct measurement, does not affect the quantity actually measured but does affect the relation between the indication and the result — ambient temperature is the classic example.
VIM (JCGM 200:2012) 2.52 · General
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.
VIM (JCGM 200:2012) 2.50 · Uncertainty
Instrument bias
The average of replicate indications minus a reference quantity value — the instrument-level counterpart of measurement bias.
VIM (JCGM 200:2012) 4.20 · Instruments
Instrumental drift
A continuous or incremental change of an indication over time, due neither to a change in the quantity being measured nor to a recognized influence quantity — a key input to calibration-interval decisions.
VIM (JCGM 200:2012) 4.21 · Instruments
Instrumental measurement uncertainty
The component of measurement uncertainty arising from the instrument or system in use, typically obtained from its calibration.
VIM (JCGM 200:2012) 4.24 · Instruments
Interlaboratory comparison
Organization, performance, and evaluation of measurements on the same or similar items by two or more laboratories under predetermined conditions.
ISO/IEC 17043:2023 · Quality & Accreditation
Intermediate measurement precision
Measurement precision under intermediate precision conditions — the realistic "within-lab, over months" figure that belongs in most uncertainty budgets.
VIM (JCGM 200:2012) 2.23 · Statistics
Intermediate precision condition
A condition set spanning the same procedure and location over an extended period, allowing other factors (operator, reference standard, time) to vary.
VIM (JCGM 200:2012) 2.22 · Statistics
International System of Quantities (ISQ)
The system of quantities based on the seven base quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity — the quantity framework beneath the SI.
VIM (JCGM 200:2012) 1.6 · Standards & Units
International System of Units (SI)
The system of units based on the ISQ, with unit names, symbols, prefixes, and rules for their use, adopted by the CGPM. Since the 2019 revision all seven base units are defined by fixing the numerical values of seven defining constants.
VIM (JCGM 200:2012) 1.16 · Standards & Units
International measurement standard
A standard recognized by signatories to an international agreement and intended to serve worldwide.
VIM (JCGM 200:2012) 5.2 · Standards & Units
Intrinsic measurement standard
A standard based on an inherent and reproducible property of a phenomenon or substance — the triple point of water cell, the Josephson voltage standard.
VIM (JCGM 200:2012) 5.10 · Standards & Units