ISO 5725-1:1994 測定方法と結果の精度（真実性と精度）—パート1：一般原則と定義 | ページ 6

3.1

observed value

The value of a characteristic obtained as the result of a single observation.

[SOURCE: ISO 3534-1]

3.2

test result

The value of a characteristic obtained by carrying out a specified test method.

Note 1 to entry: The test method should specify that one or a number of individual observations be made, and their average or another appropriate function (such as the median or the standard deviation) be reported as the test result. It may also require standard corrections to be applied, such as correction of gas volumes to standard temperature and pressure. Thus a test result can be a result calculated from several observed values. In the simple case, the test result is the observed value itself.

[SOURCE: ISO 3534-1]

3.3

level of the test in a precision experiment

The general average of the test results from all laboratories for one particular material or specimen tested.

3.4

cell in a precision experiment

The test results at a single level obtained by one laboratory.

3.5

accepted reference value

[SOURCE: ISO 3534-1]

3.6

accuracy

The closeness of agreement between a test result and the accepted reference value.

Note 1 to entry: The term accuracy, when applied to a set of test results, involves a combination of random components and a common systematic error or bias component.

[SOURCE: ISO 3534-1]

3.7

trueness

The closeness of agreement between the average value obtained from a large series of test results and an accepted reference value.

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

Note 2 to entry: Trueness has been referred to as"accuracy of the mean". This usage is not recommended.

[SOURCE: ISO 3534-1]

3.8

bias

The difference between the expectation of the test results and an accepted reference 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 accepted reference value is reflected by a larger bias value.

[SOURCE: ISO 3534-1]

3.9

laboratory bias

The difference between the expectation of the test results from a particular laboratory and an accepted reference value.

3.10

bias of the measurement method

The difference between the expectation of test results obtained from all laboratories using that method and an accepted reference value.

Note 1 to entry: One example of this in operation would be where a method purporting to measure the sulfur content of a compound consistently fails to extract all the sulfur, giving a negative bias to the measurement method. The bias of the measurement method is measured by the displacement of the average of results from a large number of different laboratories all using the same method. The bias of a measurement method may be different at different levels.

3.11

laboratory component of bias

The difference between the laboratory bias and the bias of the measurement method.

Note 1 to entry: The laboratory component of bias is specific to a given laboratory and the conditions of measurement within the laboratory, and also it may be different at different levels of the test.

Note 2 to entry: The laboratory component of bias is relative to the overall average result, not the true or reference value.

3.12

precision

The closeness of agreement between independent test 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. Less precision is reflected by a larger standard deviation.

Note 3 to entry:"Independent test results" means results obtained in a manner not influenced by any previous result on the same or similar test object. Quantitative measures of precision depend critically on the stipulated conditions. Repeatability and reproducibility conditions are particular sets of extreme conditions.

[SOURCE: ISO 3534-1]

3.13

repeatability

Precision under repeatability conditions.

[SOURCE: ISO 3534-1]

3.14

repeatability conditions

Conditions where independent test results are obtained with the same method on identical test items in the same laboratory by the same operator using the same equipment within short intervals of time.

[SOURCE: ISO 3534-1]

3.15

repeatability standard deviation

The standard deviation of test results obtained under repeatability conditions.

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

Note 2 to entry: Similarly"repeatability variance" and"repeatability coefficient of variation" could be defined and used as measures of the dispersion of test results under repeatability conditions.

[SOURCE: ISO 3534-1]

3.16

repeatability limit

The value less than or equal to which the absolute difference between two test results obtained under repeatability conditions may be expected to be with a probability of 95 %.

Note 1 to entry: The symbol used is r.

[SOURCE: ISO 3534-1]

3.17

reproducibility

Precision under reproducibility conditions.

[SOURCE: ISO 3534-1]

3.18

reproducibility conditions

Conditions where test results are obtained with the same method on identical test items in different laboratories with different operators using different equipment.

[SOURCE: ISO 3534-1]

3.19

reproducibility standard deviation

The standard deviation of test results obtained under reproducibility conditions.

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

Note 2 to entry: Similarly"reproducibility variance" and"reproducibility coefficient of variation" could be defined and used as measures of the dispersion of test results under reproducibility conditions.

[SOURCE: ISO 3534-1]

3.20

reproducibility limit

The value less than or equal to which the absolute difference between two test results obtained under reproducibility conditions may be expected to be with a probability of 95 %.

Note 1 to entry: The symbol used is R.

[SOURCE: ISO 3534-1]

3.21

outlier

A member of a set of values which is inconsistent with the other members of that set.

Note 1 to entry: ISO 5725-2 specifies the statistical tests and the significance level to be used to identify outliers in trueness and precision experiments.

3.22

collaborative assessment experiment

An interlaboratory experiment in which the performance of each laboratory is assessed using the same standard measurement method on identical material.

Note 1 to entry: The definitions given in 3.16 and 3.20 apply to results that vary on a continuous scale. If the test result is discrete or rounded off, the repeatability limit and the reproducibility limit as defined above are each the minimum value equal to or below which the absolute difference between two single test results is expected to lie with a probability of not less than 95 %.

Note 2 to entry: The definitions given in 3.8 to 3.11, 3.15, 3.16, 3.19 and 3.20 refer to theoretical values which in reality remain unknown. The values for reproducibility and repeatability standard deviations and bias actually determined by experiment (as described in ISO 5725-2 and ISO 5725-4) are, in statistical terms, estimates of these values, and as such are subject to errors. Consequently, for example, the probability levels associated with the limits r and R will not be exactly 95 %. They will approximate to 95 % when many laboratories have taken part in the precision experiment, but may be considerably different from 95 % when fewer than 30 laboratories have participated. This is unavoidable but does not seriously detract from their practical utility as they are primarily designed to serve as tools for judging whether the difference between results could be ascribed to random uncertainties inherent in the measurement method or not. Differences larger than the repeatability limit r or the reproducibility limit R are suspect.

Note 3 to entry: The symbols r and R are already in general use for other purposes; in ISO 3534-1 r is recommended for the correlation coefficient and R (or W) for the range of a single series of observations. However, there should be no confusion if the full wordings repeatability limit r and reproducibility limit R are used whenever there is a possibility of misunderstanding, particularly when they are quoted in standards.