ISO 21748:2017 測定の不確かさの評価における再現性、再現性、および真偽の推定値の使用に関するガイダンス | ページ 6

3.1

bias

difference between the expectation of a test result or measurement result and a true value

Note 1 to entry: Bias is the total systematic error as contrasted to random error. There may be one or more systematic error components contributing to the bias. A larger systematic difference from the true value is reflected by a larger bias value.

Note 2 to entry: The bias of a measuring instrument is normally estimated by averaging the error of indication over an appropriate number of repeated measurements. The error of indication is the “indication of a measuring instrument minus a true value of the corresponding input quantity”.

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

[SOURCE:ISO 3534‑2:2006, 3.3.2]

3.2

combined standard uncertainty

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:ISO/IEC Guide 98‑3:2008, 2.3.4]

3.3

coverage factor

numerical factor used as a multiplier of the combined standard uncertainty (3.2) in order to obtain an expanded uncertainty (3.4)

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

[SOURCE:ISO/IEC Guide 98‑3:2008, 2.3.6]

3.4

expanded uncertainty

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

Note 1 to entry: The fraction may be regarded as the coverage probability or level of confidence of the interval.

Note 2 to entry: To associate a specific level of confidence with the interval defined by the expanded uncertainty requires explicit or implicit assumptions regarding the probability distribution characterized by the measurement result and its combined standard uncertainty (3.2) . The level of confidence that may be attributed to this interval can be known only to the extent to which such assumptions can be justified.

Note 3 to entry: Expanded uncertainty is termed overall uncertainty in paragraph 5 of Reference [20].

[SOURCE:ISO/IEC Guide 98‑3:2008, 2.3.5]

3.5

precision

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

Note 1 to entry: Precision depends only on the distribution of random errors and does not relate to the true value or the specified value.

Note 2 to entry: The measure of precision is usually expressed in terms of imprecision and computed as a standard deviation of the test results or measurement results. Less precision is reflected by a larger standard deviation.

Note 3 to entry: Quantitative measures of precision depend critically on the stipulated conditions. Repeatability conditions (3.7) and reproducibility conditions (3.10) are particular sets of extreme stipulated conditions.

[SOURCE:ISO 3534‑2:2006, 3.3.4]

3.6

repeatability

precision (3.5) under repeatability conditions (3.7)

Note 1 to entry: Repeatability can be expressed quantitatively in terms of the dispersion characteristics of the results.

[SOURCE:ISO 3534‑2:2006, 3.3.5]

3.7

repeatability conditions

observation conditions where independent test/measurement results are 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

[SOURCE:ISO 3534‑2:2006, 3.3.6]

3.8

repeatability standard deviation

standard deviation of test results or measurement results obtained under repeatability conditions (3.7)

Note 1 to entry: It is a measure of the dispersion of the distribution of test or measurement results under repeatability conditions.

Note 2 to entry: Similarly, “repeatability variance” and “repeatability coefficient of variation” can be defined and used as measures of the dispersion of test or measurement results under repeatability conditions.

[SOURCE:ISO 3534‑2:2006, 3.3.7]

3.9

reproducibility

precision (3.5) under reproducibility conditions (3.10)

Note 1 to entry: Reproducibility can be expressed quantitatively in terms of the dispersion characteristics of the results.

Note 2 to entry: Results are usually understood to be corrected results.

[SOURCE:ISO 3534‑2:2006, 3.3.10]

3.10

reproducibility conditions

observation conditions where independent test/measurement results are obtained with the same method on identical test/measurement items in different test or measurement facilities with different operators using different equipment

[SOURCE:ISO 3534‑2:2006, 3.3.11]

3.11

reproducibility standard deviation

standard deviation of test results or measurement results obtained under reproducibility conditions (3.10)

Note 1 to entry: It is a measure of the dispersion of the distribution of test or measurement results under reproducibility conditions.

Note 2 to entry: Similarly, “reproducibility variance” and “reproducibility coefficient of variation” can be defined and used as measures of the dispersion of test or measurement results under reproducibility conditions.

[SOURCE:ISO 3534‑2:2006, 3.3.12]

3.12

standard uncertainty

uncertainty (3.14) of the result of a measurement expressed as a standard deviation

[SOURCE:ISO/IEC Guide 98‑3:2008, 2.3.1]

3.13

trueness

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

Note 1 to entry: The measure of trueness is usually expressed in terms of bias (3.1) .

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]

3.14

uncertainty

<measurement> parameter, associated with the result of a measurement, which characterizes the dispersion of the values that could reasonably be attributed to the measurand

Note 1 to entry: The parameter may be, for example, a standard deviation (or a given multiple of it), or the half-width of an interval having a stated level of confidence.

Note 2 to entry: Uncertainty of measurement comprises, in general, many components. Some of these components may be estimated from the statistical distribution of the results of a series of measurements and can be characterized by experimental standard deviations. Other components, which also can be characterized by standard deviations, are estimated from assumed probability distributions based on experience or other information.

Note 3 to entry: It is understood that the result of the measurement is the best estimate of the value of the measurand, and that all components of uncertainty, including those arising from systematic effects such as components associated with corrections and reference standards, contribute to the dispersion.

[SOURCE:ISO/IEC Guide 98‑3:2008, 2.2.3]

3.15

uncertainty budget

list of sources of uncertainty (3.14) and their associated standard uncertainties, compiled with a view to evaluating a combined standard uncertainty (3.2) associated with a measurement result

Note 1 to entry: The list often includes additional information such as sensitivity coefficients (change of result with change in a quantity affecting the result), degrees of freedom for each standard uncertainty, and an identification of the means of estimating each standard uncertainty in terms of a Type A or Type B evaluation (see ISO/IEC Guide 98-3).