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GSO ISO – Standards Store – GCC Standardization Organization

Unless otherwise specified, no part of this publrcation may be reproduced or utrlized In any form or jso any means, electronrc or mechanical, rncludrng photocopyrng and mrcrofilm, wrthout permission in writing from the publisher.

Intermediate measures of the precision of a standard measurement method Specifies four intermediate measures due to changes in observation conditions time, calibration, operator and equipment within a laboratory.

Basic methods for the determination of repeatability and reproducibility of a standard measurement method. The trueness of the measurement method can be investigated by comparing the accepted reference value with the level of the results given by the measurement method. Accuracy trueness and precision of measurement methods and results – Part 3: In the latter case, it is necessary to investigate the causes of the discrep- ancy and possibly to repeat the experiment prior to proceeding further.

In chemical anal- ysis, problems may arise from, for example, insufficient control of temperature, moisture, pres- ence of contaminants, etc. In the latter case, a careful examination of the working conditions of each laboratory shall be carried out before the assessment of the bias of the standard measurement method is undertaken. Alternative methods for the determi- nation of the precision of a standard measure- ment method.

However, for practical reasons, the choice of the number of laboratories is usually a compromise between the availability of re- sources and the desire to reduce the value of 6, to a satisfactory level. A Awar G 1, The analytical results are listed in tableB. Annexes B, C and D are for information only. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

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Thus results from each laboratory can be considered as replicates under repeatability conditions. Laboratory means and laboratory variances Lab. When gR is larger than T. There are three cases, as follows. Accuracy trueness and precision of measurement methods and results – Part 2: Basic method for the determination of repeatability and re- producibility of a standard measurement method – Part 3: Learn more about the cookies we use and how to change your settings.

ISO Accuracy of measurement methods and results-Part 2 Basic method – MBA智库文档

The laboratory means and vari- ances for each of the five test materials are listed in table 8. Each laboratory re- ceived two randomly selected bottles of test sample for each level and performed duplicate analyses on each bottle.

The variation of the 57252 of the bias of the measurement method is due to the variation in the results of the measurement process and is expressed by its standard deviation computed as in the case of known precision values, or siJzT-yF . Analysis of the results showed that the between- bottle variation was indeed insignificant; the sample was considered to be homogeneous. Reference materials could be either a certified reference materials; b 5725- manufactured for the purpose of the experiment with known properties; or c materials whose properties have been established by measurements using an alternative measure- ment method whose bias is known to be negligi- ble.

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C Derivation of equations The reference material should have a matrix as close as possible to the matrix of the material to be subjected to the standard measurement method, e.

Utilization of trueness data Refer to clause 7 of IS0 57252- If the repeatability of the measurement method is poor, then it will not be practical to achieve a high degree of certainty in the estimate of the bias of the laboratory. The test results for each level are shown in figures B.

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57225-2

Annex B provides practical examples of estimating the precision of measurement methods by experiment. IAccuracy trueness and precision of measurement methods and results – Part 1: If it is proposed to undertake an experiment to estimate laboratory bias, then it should be realized that the estimate will be valid only at the time of the ex- periment. In order for the results of an experiment to be able to detect with a high probability see annex Cl a prede- termined magnitude of bias, the minimum number of laboratories, p, and test results, n, shall satisfy the following equation: This implies comparison between the within-laboratory standard deviation and the stated repeatability standard deviation of the standard measurement method.

General principles and definitions. All standards are subject to revision, and parties to agreements based on this part of IS0 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.

BS ISO 5725-2:1994

What action is to be taken concerning its publication? This requires an experiment involving many laboratories, very much as described in IS0 Unless otherwise stated, a is assumed to be 0, IS0 consists of the following parts, under the general title Accuracy trueness and precision of measurement methods and results: There again, appropriate action should be taken by investigating these laboratories, or, if necessary, by tightening the protocol of the measurement method.

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