Notes

NOTE 1 The specification of a measurand requires knowledge of the kind of quantity, description of the state of the phenomenon, body, or substance carrying the quantity, including any relevant component, and the chemical entities involved.

NOTE 2 In the second edition of the VIM and in IEC 60050-300:2001, the measurand is defined as the 'particular quantity subject to measurement'.

NOTE 3 The measurement, including the measuring system and the conditions under which the measurement is carried out, might change the phenomenon, body, or substance such that the quantity being measured may differ from the measurand as defined. In this case, adequate correction is necessary.

EXAMPLE 1 The potential difference between the terminals of a battery may decrease when using a voltmeter with a significant internal conductance to perform the measurement. The open-circuit potential difference can be calculated from the internal resistances of the battery and the voltmeter.

EXAMPLE 2 The length of a steel rod in equilibrium with the ambient Celsius temperature of 23 °C will be different from the length at the specified temperature of 20 °C, which is the measurand. In this case, a correction is necessary.

NOTE 4 In chemistry, “analyte”, or the name of a substance or compound, are terms sometimes used for 'measurand'. This usage is erroneous because these terms do not refer to quantities.

Annotations

ANNOTATION (informative) [5 June 2014] As Note 2 says, this definition differs from the definition in VIM2. The quantity that is being measured may not actually be the quantity that is intended to be measured. By making this distinction, it is often possible to include corrections in the measurement model such that the value of the quantity that is intended to be measured can be calculated on the basis of the value of the quantity that is actually measured.

1 Quantities and units

• 1.1 quantity
• 1.2 kind of quantity
• 1.3 system of quantities
• 1.4 base quantity
• 1.5 derived quantity
• 1.6 International System of Quantities
• 1.7 quantity dimension
• 1.8 quantity of dimension one
• 1.9 measurement unit
• 1.10 base unit
• 1.11 derived unit
• 1.12 coherent derived unit
• 1.13 system of units
• 1.14 coherent system of units
• 1.15 off-system measurement unit
• 1.16 International System of Units
• 1.17 multiple of a unit
• 1.18 submultiple of a unit
• 1.19 quantity value
• 1.20 numerical quantity value
• 1.21 quantity calculus
• 1.22 quantity equation
• 1.23 unit equation
• 1.24 conversion factor between units
• 1.25 numerical value equation
• 1.26 ordinal quantity
• 1.27 quantity-value scale
• 1.28 ordinal quantity-value scale
• 1.29 conventional reference scale
• 1.30 nominal property

2 Measurement

• 2.1 measurement
• 2.2 metrology
• 2.3 measurand
• 2.4 measurement principle
• 2.5 measurement method
• 2.6 measurement procedure
• 2.7 reference measurement procedure
• 2.8 primary reference measurement procedure
• 2.9 measurement result
• 2.10 measured quantity value
• 2.11 true quantity value
• 2.12 conventional quantity value
• 2.13 measurement accuracy
• 2.14 measurement trueness
• 2.15 measurement precision
• 2.16 measurement error
• 2.17 systematic measurement error
• 2.18 measurement bias
• 2.19 random measurement error
• 2.20 repeatability condition of measurement
• 2.21 measurement repeatability
• 2.22 intermediate precision condition of measurement
• 2.23 intermediate measurement precision
• 2.24 reproducibility condition of measurement
• 2.25 measurement reproducibility
• 2.26 measurement uncertainty
• 2.27 definitional uncertainty
• 2.28 Type A evaluation of measurement uncertainty
• 2.29 Type B evaluation of measurement uncertainty
• 2.30 standard measurement uncertainty
• 2.31 combined standard measurement uncertainty
• 2.32 relative standard measurement uncertainty
• 2.33 uncertainty budget
• 2.34 target measurement uncertainty
• 2.35 expanded measurement uncertainty
• 2.36 coverage interval
• 2.37 coverage probability
• 2.38 coverage factor
• 2.39 calibration
• 2.40 calibration hierarchy
• 2.41 metrological traceability
• 2.42 metrological traceability chain
• 2.43 metrological traceability to a measurement unit
• 2.44 verification
• 2.45 validation
• 2.46 metrological comparability of measurement results
• 2.47 metrological compatibility of measurement results
• 2.48 measurement model
• 2.49 measurement function
• 2.50 input quantity in a measurement model
• 2.51 output quantity in a measurement model
• 2.52 influence quantity
• 2.53 correction

3 Devices for measurement

• 3.1 measuring instrument
• 3.2 measuring system
• 3.3 indicating measuring instrument
• 3.4 displaying measuring instrument
• 3.5 scale of a displaying measuring instrument
• 3.6 material measure
• 3.7 measuring transducer
• 3.8 sensor
• 3.9 detector
• 3.10 measuring chain
• 3.11 adjustment of a measuring system
• 3.12 zero adjustment of a measuring system

4 Properties of measuring devices

• 4.1 indication
• 4.2 blank indication
• 4.3 indication interval
• 4.4 nominal indication interval
• 4.5 range of a nominal indication interval
• 4.6 nominal quantity value
• 4.7 measuring interval
• 4.8 steady-state operating condition
• 4.9 rated operating condition
• 4.10 limiting operating condition
• 4.11 reference operating condition
• 4.12 sensitivity of a measuring system
• 4.13 selectivity of a measuring system
• 4.14 resolution
• 4.15 resolution of a displaying device
• 4.16 discrimination threshold
• 4.17 dead band
• 4.18 detection limit
• 4.19 stability of a measuring instrument
• 4.20 instrumental bias
• 4.21 instrumental drift
• 4.22 variation due to an influence quantity
• 4.23 step response time
• 4.24 instrumental measurement uncertainty
• 4.25 accuracy class
• 4.26 maximum permissible measurement error
• 4.27 datum measurement error
• 4.28 zero error
• 4.29 null measurement uncertainty
• 4.30 calibration diagram
• 4.31 calibration curve

5 Measurement standards (Etalons)

• 5.1 measurement standard
• 5.2 international measurement standard
• 5.3 national measurement standard
• 5.4 primary measurement standard
• 5.5 secondary measurement standard
• 5.6 reference measurement standard
• 5.7 working measurement standard
• 5.8 travelling measurement standard
• 5.9 transfer measurement device
• 5.10 intrinsic measurement standard
• 5.11 conservation of a measurement standard
• 5.12 calibrator
• 5.13 reference material
• 5.14 certified reference material
• 5.15 commutability of a reference material
• 5.16 reference data
• 5.17 standard reference data
• 5.18 reference quantity value