Every concept appears with its definition (if any) and its relationships to other terms.
class of measuring instruments or measuring systems that meet stated metrological requirements that are intended to keep measurement errors or instrumental measurement uncertainties within specified limits under specified operating conditions.
set of operations carried out on a measuring system so that it provides prescribed indications corresponding to given values of a quantity to be measured.
quantity in a conventionally chosen subset of a given system of quantities, where no subset quantity can be expressed in terms of the others.
measurement unit that is adopted by convention for a base quantity.
indication obtained from a phenomenon, body, or substance similar to the one under investigation, but for which a quantity of interest is supposed not to be present, or is not contributing to the indication.
operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication.
expression of the relation between indication and corresponding measured quantity value.
graphical expression of the relation between indication and corresponding measurement result.
sequence of calibrations from a reference to the final measuring system, where the outcome of each calibration depends on the outcome of the previous calibration.
measurement standard used in calibration.
reference material, accompanied by documentation issued by an authoritative body and providing one or more specified property values with associated uncertainties and traceabilities, using valid procedures.
derived unit that, for a given system of quantities and for a chosen set of base units, is a product of powers of base units with no other proportionality factor than one.
system of units, based on a given system of quantities, in which the measurement unit for each derived quantity is a coherent derived unit.
standard measurement uncertainty that is obtained using the individual standard measurement uncertainties associated with the input quantities in a measurement model.
property of a reference material, demonstrated by the closeness of agreement between the relation among the measurement results for a stated quantity in this material, obtained according to two given measurement procedures, and the relation obtained among the measurement results for other specified materials.
set of operations necessary to preserve the metrological properties of a measurement standard within stated limits.
quantity value attributed by agreement to a quantity for a given purpose.
quantity-value scale defined by formal agreement.
ratio of two measurement units for quantities of the same kind.
number larger than one by which a combined standard measurement uncertainty is multiplied to obtain an expanded measurement uncertainty.
interval containing the set of true quantity values of a measurand with a stated probability, based on the information available.
probability that the set of true quantity values of a measurand is contained within a specified coverage interval.
measurement error of a measuring instrument or measuring system at a specified measured quantity value.
maximum interval through which a value of a quantity being measured can be changed in both directions without producing a detectable change in the corresponding indication.
component of measurement uncertainty resulting from the finite amount of detail in the definition of a measurand.
quantity, in a system of quantities, defined in terms of the base quantities of that system.
measurement unit for a derived quantity.
measured quantity value, obtained by a given measurement procedure, for which the probability of falsely claiming the absence of a component in a material is β, given a probability α of falsely claiming its presence.
device or substance that indicates the presence of a phenomenon, body, or substance when a threshold value of an associated quantity is exceeded.
largest change in a value of a quantity being measured that causes no detectable change in the corresponding indication.
indicating measuring instrument where the output signal is presented in visual form.
product of a combined standard measurement uncertainty and a factor larger than the number one.
measuring instrument providing an output signal carrying information about the value of the quantity being measured.
quantity value provided by a measuring instrument or a measuring system.
set of quantity values bounded by extreme possible indications.
quantity that, in a direct measurement, does not affect the quantity that is actually measured, but affects the relation between the indication and the measurement result.
quantity that must be measured, or a quantity, the value of which can be otherwise obtained, in order to calculate a measured quantity value of a measurand.
average of replicate indications minus a reference quantity value.
continuous or incremental change over time in indication, due to changes in metrological properties of a measuring instrument.
component of measurement uncertainty arising from a measuring instrument or measuring system in use.
measurement precision under a set of intermediate precision conditions of measurement.
condition of measurement, out of a set of conditions that includes the same measurement procedure, same location, and replicate measurements on the same or similar objects over an extended period of time, but may include other conditions involving changes.
measurement standard recognized by signatories to an international agreement and intended to serve worldwide.
system of quantities based on the seven base quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity.
system of units, based on the International System of Quantities, their names and symbols, including a series of prefixes and their names and symbols, together with rules for their use, adopted by the General Conference on Weights and Measures (CGPM).
measurement standard based on an inherent and reproducible property of a phenomenon or substance.
extreme operating condition that a measuring instrument or measuring system is required to withstand without damage, and without degradation of specified metrological properties, when it is subsequently operated under its rated operating conditions.
measuring instrument reproducing or supplying, in a permanent manner during its use, quantities of one or more given kinds, each with an assigned quantity value.
extreme value of measurement error, with respect to a known reference quantity value, permitted by specifications or regulations for a given measurement, measuring instrument, or measuring system.
quantity intended to be measured.
quantity value representing a measurement result.
process of experimentally obtaining one or more quantity values that can reasonably be attributed to a quantity.
closeness of agreement between a measured quantity value and a true quantity value of a measurand.
estimate of a systematic measurement error.
measured quantity value minus a reference quantity value.
function of quantities, the value of which, when calculated using known quantity values for the input quantities in a measurement model, is a measured quantity value of the output quantity in the measurement model.
generic description of a logical organization of operations used in a measurement.
mathematical relation among all quantities known to be involved in a measurement.
closeness of agreement between indications or measured quantity values obtained by replicate measurements on the same or similar objects under specified conditions.
phenomenon serving as a basis of a measurement.
detailed description of a measurement according to one or more measurement principles and to a given measurement method, based on a measurement model and including any calculation to obtain a measurement result.
measurement precision under a set of repeatability conditions of measurement.
measurement precision under reproducibility conditions of measurement.
set of quantity values being attributed to a measurand together with any other available relevant information.
realization of the definition of a given quantity, with stated quantity value and associated measurement uncertainty, used as a reference.
closeness of agreement between the average of an infinite number of replicate measured quantity values and a reference quantity value.
non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used.
real scalar quantity, defined and adopted by convention, with which any other quantity of the same kind can be compared to express the ratio of the two quantities as a number.
series of elements of a measuring system constituting a single path of the signal from a sensor to an output element.
device used for making measurements, alone or in conjunction with one or more supplementary devices.
set of values of quantities of the same kind that can be measured by a given measuring instrument or measuring system with specified instrumental measurement uncertainty, under defined conditions.
set of one or more measuring instruments and often other devices, including any reagent and supply, assembled and adapted to give information used to generate measured quantity values within specified intervals for quantities of specified kinds.
device, used in measurement, that provides an output quantity having a specified relation to the input quantity.
comparability of measurement results, for quantities of a given kind, that are metrologically traceable to the same reference.
property of a set of measurement results for a specified measurand, such that the absolute value of the difference of any pair of measured quantity values from two different measurement results is smaller than some chosen multiple of the standard measurement uncertainty of that difference.
property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.
sequence of measurement standards and calibrations that is used to relate a measurement result to a reference.
metrological traceability where the reference is the definition of a measurement unit through its practical realization.
measurement unit obtained by multiplying a given measurement unit by an integer greater than one.
measurement standard recognized by national authority to serve in a state or economy as the basis for assigning quantity values to other measurement standards for the kind of quantity concerned.
set of quantity values, bounded by rounded or approximate extreme indications, obtainable with a particular setting of the controls of a measuring instrument or measuring system and used to designate that setting.
property of a phenomenon, body, or substance, where the property has no magnitude.
rounded or approximate value of a characterizing quantity of a measuring instrument or measuring system that provides guidance for its appropriate use.
measurement uncertainty where the specified measured quantity value is zero.
number in the expression of a quantity value, other than any number serving as the reference.
mathematical relation between numerical quantity values, based on a given quantity equation and specified measurement units.
measurement unit that does not belong to a given system of units.
quantity, defined by a conventional measurement procedure, for which a total ordering relation can be established, according to magnitude, with other quantities of the same kind, but for which no algebraic operations among those quantities exist.
quantity-value scale for ordinal quantities.
quantity, the measured value of which is calculated using the values of input quantities in a measurement model.
measurement standard established using a primary reference measurement procedure, or created as an artifact, chosen by convention.
reference measurement procedure used to obtain a measurement result without relation to a measurement standard for a quantity of the same kind.
property of a phenomenon, body, or substance, where the property has a magnitude that can be expressed as a number and a reference.
set of mathematical rules and operations applied to quantities other than ordinal quantities.
expression of the dependence of a quantity on the base quantities of a system of quantities as a product of powers of factors corresponding to the base quantities, omitting any numerical factor.
mathematical relation between quantities in a given system of quantities, independent of measurement units.
quantity for which all the exponents of the factors corresponding to the base quantities in its quantity dimension are zero.
number and reference together expressing magnitude of a quantity.
ordered set of quantity values of quantities of a given kind of quantity used in ranking, according to magnitude, quantities of that kind.
component of measurement error that in replicate measurements varies in an unpredictable manner.
absolute value of the difference between the extreme quantity values of a nominal indication interval.
operating condition that must be fulfilled during measurement in order that a measuring instrument or measuring system perform as designed.
data related to a property of a phenomenon, body, or substance, or to a system of components of known composition or structure, obtained from an identified source, critically evaluated, and verified for accuracy.
material, sufficiently homogeneous and stable with reference to specified properties, which has been established to be fit for its intended use in measurement or in examination of nominal properties.
measurement procedure accepted as providing measurement results fit for their intended use in assessing measurement trueness of measured quantity values obtained from other measurement procedures for quantities of the same kind, in calibration, or in characterizing reference materials.
measurement standard designated for the calibration of other measurement standards for quantities of a given kind in a given organization or at a given location.
operating condition prescribed for evaluating the performance of a measuring instrument or measuring system or for comparison of measurement results.
quantity value used as a basis for comparison with values of quantities of the same kind.
standard measurement uncertainty divided by the absolute value of the measured quantity value.
condition of measurement, out of a set of conditions that includes the same measurement procedure, same operators, same measuring system, same operating conditions and same location, and replicate measurements on the same or similar objects over a short period of time.
condition of measurement, out of a set of conditions that includes different locations, operators, measuring systems, and replicate measurements on the same or similar objects.
smallest change in a quantity being measured that causes a perceptible change in the corresponding indication.
smallest difference between displayed indications that can be meaningfully distinguished.
part of a displaying measuring instrument, consisting of an ordered set of marks together with any associated quantity values.
measurement standard established through calibration with respect to a primary measurement standard for a quantity of the same kind.
property of a measuring system, used with a specified measurement procedure, whereby it provides measured quantity values for one or more measurands such that the values of each measurand are independent of other measurands or other quantities in the phenomenon, body, or substance being investigated.
quotient of the change in an indication of a measuring system and the corresponding change in a value of a quantity being measured.
element of a measuring system that is directly affected by a phenomenon, body, or substance carrying a quantity to be measured.
property of a measuring instrument, whereby its metrological properties remain constant in time.
measurement uncertainty expressed as a standard deviation.
operating condition of a measuring instrument or measuring system in which the relation established by calibration remains valid even for a measurand varying with time.
duration between the instant when an input quantity value of a measuring instrument or measuring system is subjected to an abrupt change between two specified constant quantity values and the instant when a corresponding indication settles within specified limits around its final steady value.
measurement unit obtained by dividing a given measurement unit by an integer greater than one.
component of measurement error that in replicate measurements remains constant or varies in a predictable manner.
set of quantities together with a set of noncontradictory equations relating those quantities.
set of base units and derived units, together with their multiples and submultiples, defined in accordance with given rules, for a given system of quantities.
measurement uncertainty specified as an upper limit and decided on the basis of the intended use of measurement results.
device used as an intermediary to compare measurement standards.
measurement standard, sometimes of special construction, intended for transport between different locations.
quantity value consistent with the definition of a quantity.
evaluation of a component of measurement uncertainty by a statistical analysis of measured quantity values obtained under defined measurement conditions.
evaluation of a component of measurement uncertainty determined by means other than a Type A evaluation of measurement uncertainty.
statement of a measurement uncertainty, of the components of that measurement uncertainty, and of their calculation and combination.
mathematical relation between base units, coherent derived units or other measurement units.
verification, where the specified requirements are adequate for an intended use.
difference in indication for a given measured quantity value, or in quantity values supplied by a material measure, when an influence quantity assumes successively two different quantity values.
provision of objective evidence that a given item fulfils specified requirements.
measurement standard that is used routinely to calibrate or verify measuring instruments or measuring systems.
adjustment of a measuring system so that it provides a null indication corresponding to a zero value of a quantity to be measured.
datum measurement error where the specified measured quantity value is zero.