ISO 14807:2001 写真—透過および反射濃度計—性能を決定する方法 | ページ 6

3.1

true value (of a quantity)

value consistent with the definition of a given particular quantity

Note 1 to entry: This is a value that would be obtained by a perfect measurement.

Note 2 to entry: True values are by nature indeterminate.

Note 3 to entry: The indefinite article “a”, rather than the definite article “the”, is used in conjunction with “true value” because there may be many values consistent with the definition of a given particular quantity.

[SOURCE: VIM:1993, 1.19]

3.2

conventional true value (of a quantity)

value attributed to a particular quantity and accepted, sometimes by convention, as having an uncertainty appropriate for a given purpose

[SOURCE: VIM:1993, 1.20]

Note 1 to entry: “Conventional true value” is sometimes called assigned value, best estimate of the value, conventional value or reference value .

Note 2 to entry: An assigned value of a certified reference material is one type of conventional true value.

3.3

measurand

particular quantity subject to measurement

Note 1 to entry: The specification of a measurand may require statements about quantities such as time, temperature and pressure.

[SOURCE: VIM:1993, 2.6]

3.4

repeatability (of results of measurements)

closeness of the agreement between the results of successive measurements of the same measurand carried out under the same conditions of measurement

Note 1 to entry: These conditions are called repeatability conditions .

Note 3 to entry: Repeatability may be expressed quantitatively in terms of the dispersion characteristics of the results.

[SOURCE: VIM:1993, 3.6]

3.5

experimental standard deviation

s

[SOURCE: VIM:1993, 3.8]

3.6

systematic error

mean that would result from an infinite number of measurements of the same measurand carried out under repeatability conditions minus a true value of the measurand

[SOURCE: VIM:1993, 3.14]

Note 1 to entry: Like true value, systematic error and its causes cannot be completely known.

3.7

stability

ability of a measuring instrument to maintain constant its metrological characteristics with time

Note 1 to entry: Where stability with respect to a quantity other than time is considered, this should be stated explicitly.

[SOURCE: VIM:1993, 5.14]

3.8

error (of indication) of a measuring instrument

indication of a measuring instrument minus a true value of the corresponding input quantity

[SOURCE: VIM:1993, 5.20]

3.9

bias (of a measuring instrument)

systematic error of the indication of a measuring instrument

Note 1 to entry: The bias of a measuring instrument is normally estimated by averaging the error of indication over an appropriate number of repeated measurements.

[SOURCE: VIM:1993, 5.25]

3.10

traceability

property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties

Note 1 to entry: The concept is often expressed by the adjective traceable .

Note 2 to entry: The unbroken chain of comparisons is called a traceability chain .

[SOURCE: VIM:1993, 6.10]

3.11

calibration

set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring instrument or measuring system, or values represented by a material measure or a reference material, and the corresponding values realized by standards

[SOURCE: VIM:1993, 6.11]

3.12

reference material (RM)

material or substance one or more of whose property values are sufficiently homogeneous and well established to be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to materials

[SOURCE: VIM:1993, 6.13]

3.13

certified reference material (CRM)

reference material, accompanied by a certificate, one or more of whose property values are certified by a procedure which establishes traceability to an accurate realisation of the unit in which the property values are expressed, and for which each certified value is accompanied by an uncertainty at a stated level of confidence

[SOURCE: VIM:1993, 6.14]

3.14

combined standard uncertainty

u_c

standard uncertainty of the result of a measurement when that result is obtained from the values of a number of other quantities, equal to the positive square root of a sum of terms, the terms being the variances or covariances of these other quantities weighted according to how the measurement result varies with changes in these quantities

[SOURCE: [2.3.4 of the Guide to the Expression of Uncertainty in Measurement:1993 ^[1].]]

3.15

coverage factor

k

numerical factor used as a multiplier of the combined standard uncertainty in order to obtain an expanded uncertainty

Note 1 to entry: A coverage factor, k , is typically in the range 2 to 3.

Note 2 to entry: The coverage factor is chosen based on the level of confidence desired. A coverage factor ( k ) of 2 generally will result in a level of confidence of approximately 95 %, and a coverage factor of 3 generally will result in a level of confidence of approximately 99 %. This association of confidence level and coverage factor is based on assumptions regarding the probability distribution of measurement results. For a more thorough explanation, the Guide to the Expression of Uncertainty in Measurement: 1993 ^[1] should be consulted.

[SOURCE: [This definition and the first note are taken from 2.3.6 of the Guide to the Expression of Uncertainty in Measurement:1993 ^[1].]]

3.16

expanded uncertainty

U

quantity defining an interval about the result of a measurement that may be expected to encompass a large fraction of the distribution of values that could reasonably be attributed to the measurand

[SOURCE: [2.3.5 of the Guide to the Expression of Uncertainty in Measurement:1993 ^[1].]]

Note 1 to entry: Expanded uncertainty is the product of the combined standard uncertainty ( u_c) and the chosen coverage factor ( k ).