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.
Accuracy class
A class of instruments or systems that meet stated metrological requirements intended to keep errors or instrumental uncertainties within specified limits under specified conditions — OIML weight classes E1 through M3 are the canonical example.
VIM (JCGM 200:2012) 4.25 · Instruments
Blank indication
The indication obtained from a phenomenon, body, or substance similar to the one under investigation but for which the quantity of interest is supposed absent or not contributing — the analytical chemist's blank, generalized.
VIM (JCGM 200:2012) 4.2 · Instruments
Datum measurement error
The measurement error of an instrument or system at a specified measured value — the error quoted at a named point rather than over the whole interval.
VIM (JCGM 200:2012) 4.27 · Instruments
Dead band
The maximum interval through which the value of the quantity being measured can be changed in both directions without producing a detectable change in indication — hysteresis's operational signature.
VIM (JCGM 200:2012) 4.17 · Instruments
Detection limit
The measured value, obtained by a given procedure, for which the probability of falsely claiming absence of a component is β, given a probability α of falsely claiming its presence — the statistically honest "smallest amount we can claim to see".
VIM (JCGM 200:2012) 4.18 · Instruments
Detector
A device or substance that indicates the presence of a phenomenon, body, or substance when a threshold of an associated quantity is exceeded — presence, not magnitude.
VIM (JCGM 200:2012) 3.9 · Instruments
Discrimination threshold
The largest change in the value of the quantity being measured that causes no detectable change in the corresponding indication — stickiness quantified.
VIM (JCGM 200:2012) 4.16 · Instruments
Displaying measuring instrument
An indicating instrument whose output signal is presented in visual form.
VIM (JCGM 200:2012) 3.4 · Instruments
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
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
Limiting operating condition
An extreme operating condition an instrument is required to withstand without damage and without degrading specified properties when subsequently operated under rated conditions — survival limits, not working limits.
VIM (JCGM 200:2012) 4.10 · Instruments
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
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
Nominal indication interval
The set of values, bounded by rounded or approximate extreme indications, obtainable with a particular setting of the controls and used to designate that setting — the "0–100 V range" on a meter switch.
VIM (JCGM 200:2012) 4.4 · Instruments
Nominal quantity value
A rounded or approximate value of a characterizing quantity of a measuring instrument that guides its appropriate use — the "100 Ω" stamped on a resistor, the "1 kg" of a weight.
VIM (JCGM 200:2012) 4.6 · Instruments
Null measurement uncertainty
The measurement uncertainty when the specified measured value is zero — what limits how confidently a null or tare reading can be trusted.
VIM (JCGM 200:2012) 4.29 · Instruments
Range of a nominal indication interval
The absolute difference between the extreme values of a nominal indication interval — 200 V for the −100 V to +100 V setting.
VIM (JCGM 200:2012) 4.5 · Instruments
Rated operating condition
An operating condition that must be fulfilled during measurement for an instrument to perform as designed — the environmental and use envelope the specs assume.
VIM (JCGM 200:2012) 4.9 · Instruments
Reference operating condition
An operating condition prescribed for evaluating the performance of an instrument or for comparing results — the 23 °C ± 1 °C line at the top of a datasheet.
VIM (JCGM 200:2012) 4.11 · Instruments
Resolution
The smallest change in the quantity being measured that causes a perceptible change in the corresponding indication. Digital resolution contributes a rectangular uncertainty component of (δ/2)/√3.
VIM (JCGM 200:2012) 4.14 · Instruments
Resolution of a displaying device
The smallest difference between displayed indications that can be meaningfully distinguished — for a digital display, one count of the least significant digit.
VIM (JCGM 200:2012) 4.15 · Instruments
Scale of a displaying measuring instrument
The part of a displaying instrument consisting of an ordered set of marks with associated quantity values.
VIM (JCGM 200:2012) 3.5 · Instruments
Selectivity of a measuring system
The property whereby the system provides measured values for one or more measurands that are independent of other measurands or influence quantities.
VIM (JCGM 200:2012) 4.13 · Instruments
Sensitivity of a measuring system
The quotient of the change in an indication and the corresponding change in the value of the quantity being measured.
VIM (JCGM 200:2012) 4.12 · Instruments
Sensor
The element of a measuring system directly affected by the phenomenon, body, or substance carrying the quantity being measured — the Pt resistance element in an SPRT, the seismic mass in an accelerometer.
VIM (JCGM 200:2012) 3.8 · Instruments
Stability of a measuring instrument
The property of an instrument whereby its metrological properties remain constant in time — quantified by the time taken to drift a stated amount, or the change over a stated time.
VIM (JCGM 200:2012) 4.19 · Instruments
Steady-state operating condition
An operating condition under which the relation established by calibration remains valid even though the measurand varies with time.
VIM (JCGM 200:2012) 4.8 · Instruments
Step response time
The duration between the instant an input quantity is subjected to an abrupt change between two specified constant values and the instant the indication settles within specified limits of its final steady value.
VIM (JCGM 200:2012) 4.23 · Instruments
Variation due to an influence quantity
The difference in indication, or in the supplied quantity value of a material measure, when an influence quantity assumes two different specified values — the temperature coefficient on a datasheet is one of these.
VIM (JCGM 200:2012) 4.22 · Instruments
Zero error
The datum measurement error when the specified measured value is zero.
VIM (JCGM 200:2012) 4.28 · Instruments