ISO 8196-1:2009 ミルク—ミルク分析の代替方法の全体的な精度の定義と評価—パート1：代替方法の分析属性 | ページ 7

3.1.1

true quantity value

true value of a quantity

true value

quantity value consistent with the definition of a quantity

Note 1 to entry: In the Error Approach to describing measurement, a true quantity value is considered unique and, in practice, unknowable. The Uncertainty Approach is to recognize that, owing to the inherently incomplete amount of detail in the definition of a quantity, there is not a single true quantity value but rather a set of true quantity values consistent with the definition. However, this set of values is, in principle and in practice, unknowable. Other approaches dispense altogether with the concept of true quantity value and rely on the concept of metrological compatibility of measurement results for assessing their validity.

Note 2 to entry: In the special case of a fundamental constant, the quantity is considered to have a single true quantity value.

Note 3 to entry: When the definitional uncertainty associated with the measurand is considered to be negligible compared to the other components of the measurement uncertainty, the measurand may be considered to have an “essentially unique” true quantity value. This is the approach taken by ISO/IEC Guide 98-3:2008 ^[3] and associated documents ここで, the word “true” is considered to be redundant.

[SOURCE:ISO/IEC Guide 99:2007 ^[4] , 2.11]

3.1.2

reference method

anchor method

method of analysis internationally recognized by experts or by agreement between the parties

Note 1 to entry: Adapted from ISO 21187|IDF 196:2004 ^[1] , 3.2.

Note 2 to entry: A reference method gives the “true value” or “assigned value” of the quantity of the measurand.

3.1.3

alternative method

routine method

method of analysis allowing quantification of the status of a test sample

Note 1 to entry: Adapted from ISO 21187|IDF 196:2004 ^[1] , 3.1.

Note 2 to entry: An alternative method demonstrates or estimates, for a given category of products, the same measurand as determined using the corresponding reference method (3.1.2) .

Note 3 to entry: The alternative method can be either an indirect method — i.e. one not measuring directly the component or the characteristic that it is intended to quantify, but instead one or more quantities or properties which are functionally linked to that component — or a direct method. It can have specific adaptations for user convenience (e.g. speed, automation, miniaturization, cost) that can introduce deviation into the analytical process (e.g. incomplete component or characteristic measurement) and thus prevent direct estimation and give different accuracy.

3.2.1

precision

closeness of agreement between independent test/measurement results obtained under stipulated conditions

[SOURCE:ISO 3534-2:2006, 3.3.4]

3.2.2

repeatability limit

r

value less than or equal to which the absolute difference between two final values, each of them representing a series of test results or measurement results obtained with the same method on identical test/measurement items in the same test or measuring facility by the same operator using the same equipment within short intervals of time, is expected to be for a specified probability of 95 %

Note 1 to entry: Adapted from ISO 3534-2:2006, 3.3.6, 3.3.8, 3.3.9.

3.2.3

reproducibility limit

R

value less than or equal to which the absolute difference between two final values, each of them representing a series of test results or measurement results obtained with the same method on identical test/measurement items in different test or measuring facilities with different operators using different equipment, is expected to be for a specified probability of 95 %

Note 1 to entry: Adapted from ISO 3534-2:2006, 3.3.11, 3.3.13, 3.3.14.

3.3.1

accuracy

closeness of agreement between a test result or measurement result and the true value (3.1.1)

Note 1 to entry: In practice, the accepted reference value is substituted for the true value.

Note 2 to entry: The term accuracy, when applied to a set of test or measurement results, involves a combination of random components and a common systematic error or bias component.

Note 3 to entry: Accuracy refers to a combination of trueness (3.3.2) and precision (3.2.1) .

[SOURCE:ISO 3534-2:2006, 3.3.1]

3.3.2

trueness

closeness of agreement between the expectation of a test result or a measurement result and a true value (3.1.1)

Note 1 to entry: The measure of trueness is usually expressed in terms of bias.

Note 2 to entry: Trueness is sometimes referred to as “accuracy of the mean”. This usage is not recommended.

Note 3 to entry: In practice, the accepted reference value is substituted for the true value.

[SOURCE:ISO 3534-2:2006, 3.3.3]

3.3.3

exactness of calibration

closeness of agreement, at each level of the measurand, between an alternative method value and the estimated average true value for all individual samples at the corresponding level

3.3.4

accuracy of estimate

closeness of agreement between the average test result obtained by the reference method and an alternative method on identical materials, provided that the calibration of the alternative method is exact

Note 1 to entry: Accuracy of estimate measures the part of the systematic error not due to error in calibration.

3.4.1

selectivity

property of a method to respond exclusively to the characteristic or analyte to be measured, or degree to which a method can quantify that characteristic or analyte accurately in the presence of interferents

Note 1 to entry: As a general principle, selectivity is sufficiently good for any interference to be ignored. Selectivity contributes to trueness.

3.4.2

sensitivity

smallest change in concentration which can be measured by an analytical procedure

Note 1 to entry: Sensitivity is calculated as the ratio of the variation of the method response to the variation of analyte concentration. As this is usually arbitrary, depending on instrumental settings, it is not useful in validation. However, it may be useful in quality assurance procedures to test whether an instrument is performing to a consistent and satisfactory standard.

3.4.3

limit of detection

LOD

minimum amount or concentration of the analyte in a test sample which can be detected reliably but not necessarily quantified, as demonstrated by a collaborative trial or other appropriate validation

[SOURCE:ISO 24276:2006 ^[2] , 3.1.6]

Note 1 to entry: For instrumental methods, sensitivity and limit of detection are usually determined by the sensitivity of the detector and the signal/noise ratio.

3.4.4

limit of determination

limit of quantitation

LOQ

lowest concentration or amount of the analyte in a test sample which can be quantitatively determined with an acceptable level of precision and accuracy, as demonstrated by a collaborative trial or other appropriate validation

[SOURCE:ISO 24276:2006 ^[2] , 3.1.7]