NOTE 1 An indication may be presented in visual or acoustic form or may be transferred to another device. An indication is often given by the position of a pointer on the display for analog outputs, a displayed or printed number for digital outputs, a code pattern for code outputs, or an assigned quantity value for material measures.
NOTE 2 An indication and a corresponding value of the quantity being measured are not necessarily values of quantities of the same kind.
NOTE 1 An indication interval is usually stated in terms of its smallest and greatest quantity values, for example “99 V to 201 V”.
NOTE 2 In some fields, the term is “range of indications”.
NOTE 1 A nominal indication interval is usually stated as its smallest and greatest quantity values, for example “100 V to 200 V”.
NOTE 2 In some fields, the term is “nominal range”.
EXAMPLE For a nominal indication interval of −10 V to +10 V, the range of the nominal indication interval is 20 V.
NOTE Range of a nominal indication interval is sometimes termed “span of a nominal interval”.
EXAMPLE 1 100 Ω as the nominal quantity value marked on a standard resistor.
EXAMPLE 2 1 000 ml as the nominal quantity value marked on a single‑mark volumetric flask.
EXAMPLE 3 0.1 mol/l as the nominal quantity value for amount‑of‑substance concentration of a solution of hydrogen chloride, HCl.
EXAMPLE 4 −20 °C as a maximum Celsius temperature for storage.
NOTE “Nominal quantity value” and “nominal value” are not to be confused with “nominal property value” (see 1.30, Note 2).
NOTE 1 In some fields, the term is “measuring range” or “measurement range”.
NOTE 2 The lower limit of a measuring interval should not be confused with detection limit.
NOTE Rated operating conditions generally specify intervals of values for a quantity being measured and for any influence quantity.
NOTE 1 Limiting conditions for storage, transport or operation can differ.
NOTE 2 Limiting conditions can include limiting values of a quantity being measured and of any influence quantity.
NOTE 1 Reference operating conditions specify intervals of values of the measurand and of the influence quantities.
NOTE 2 In IEC 60050‑300, item 311‑06‑02, the term “reference condition” refers to an operating condition under which the specified instrumental measurement uncertainty is the smallest possible.
NOTE 1 Sensitivity of a measuring system can depend on the value of the quantity being measured.
NOTE 2 The change considered in a value of a quantity being measured must be large compared with the resolution.
EXAMPLE 1 Capability of a measuring system including a mass spectrometer to measure the ion current ratio generated by two specified compounds without disturbance by other specified sources of electric current.
EXAMPLE 2 Capability of a measuring system to measure the power of a signal component at a given frequency without being disturbed by signal components or other signals at other frequencies.
EXAMPLE 3 Capability of a receiver to discriminate between a wanted signal and unwanted signals, often having frequencies slightly different from the frequency of the wanted signal.
EXAMPLE 4 Capability of a measuring system for ionizing radiation to respond to a given radiation to be measured in the presence of concomitant radiation.
EXAMPLE 5 Capability of a measuring system to measure the amount‑of‑substance concentration of creatininium in blood plasma by a JaffĂ© procedure without being influenced by the glucose, urate, ketone, and protein concentrations.
EXAMPLE 6 Capability of a mass spectrometer to measure the amount‑of‑substance abundance of the 28Si isotope and of the 30Si isotope in silicon from a geological deposit without influence between the two, or from the 29Si isotope.
NOTE 1 In physics, there is only one measurand; the other quantities are of the same kind as the measurand, and they are input quantities to the measuring system.
NOTE 2 In chemistry, the measured quantities often involve different components in the system undergoing measurement and these quantities are not necessarily of the same kind.
NOTE 3 In chemistry, selectivity of a measuring system is usually obtained for quantities with selected components in concentrations within stated intervals.
NOTE 4 Selectivity as used in physics (see Note 1) is a concept close to specificity as it is sometimes used in chemistry.
NOTE Resolution can depend on, for example, noise (internal or external) or friction. It may also depend on the value of a quantity being measured.
NOTE Discrimination threshold may depend on, e.g. noise (internal or external) or friction. It can also depend on the value of the quantity being measured and how the change is applied.
NOTE Dead band can depend on the rate of change.
NOTE 1 IUPAC recommends default values for α and β equal to 0.05.
NOTE 2 The abbreviation LOD is sometimes used.
NOTE 3 The term “sensitivity” is discouraged for ‘detection limit’.
NOTE Stability may be quantified in several ways.
EXAMPLE 1 In terms of the duration of a time interval over which a metrological property changes by a stated amount.
EXAMPLE 2 In terms of the change of a property over a stated time interval.
NOTE Instrumental drift is related neither to a change in a quantity being measured nor to a change of any recognized influence quantity.
NOTE 1 Instrumental measurement uncertainty is obtained through calibration of a measuring instrument or measuring system, except for a primary measurement standard for which other means are used.
NOTE 2 Instrumental uncertainty is used in a Type B evaluation of measurement uncertainty.
NOTE 3 Information relevant to instrumental measurement uncertainty may be given in the instrument specifications.
NOTE 1 An accuracy class is usually denoted by a number or symbol adopted by convention.
NOTE 2 Accuracy class applies to material measures.
NOTE 1 Usually, the term “maximum permissible errors” or “limits of error” is used where there are two extreme values.
NOTE 2 The term “tolerance” should not be used to designate ‘maximum permissible error’.
NOTE Zero error should not be confused with absence of measurement error.
NOTE 1 Null measurement uncertainty is associated with a null or near zero indication and covers an interval where one does not know whether the measurand is too small to be detected or the indication of the measuring instrument is due only to noise.
NOTE 2 The concept of ‘null measurement uncertainty’ also applies when a difference is obtained between measurement of a sample and a blank.
NOTE 1 A calibration diagram is the strip of the plane defined by the axis of the indication and the axis of measurement result, that represents the relation between an indication and a set of measured quantity values. A one‑to‑many relation is given, and the width of the strip for a given indication provides the instrumental measurement uncertainty.
NOTE 2 Alternative expressions of the relation include a calibration curve and associated measurement uncertainty, a calibration table, or a set of functions.
NOTE 3 This concept pertains to a calibration when the instrumental measurement uncertainty is large in comparison with the measurement uncertainties associated with the quantity values of measurement standards.
NOTE A calibration curve expresses a one‑to‑one relation that does not supply a measurement result as it bears no information about the measurement uncertainty.