1、BSI Standards PublicationBS ISO 13528:2015Statistical methods for usein proficiency testing byinterlaboratory comparisonBS ISO 13528:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 13528:2015. Itsupersedes BS ISO 13528:2005 which is withdrawn.The UK partic
2、ipation in its preparation was entrusted to TechnicalCommittee SS/6, Precision of test methods.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsibl
3、e for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 73566 0ICS 03.120.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Polic
4、y and Strategy Committee on 31 August 2015.Amendments issued since publicationDate Text affectedBS ISO 13528:2015 ISO 2015Statistical methods for use in proficiency testing by interlaboratory comparisonMthodes statistiques utilises dans les essais daptitude par comparaison interlaboratoiresINTERNATI
5、ONAL STANDARDISO13528Second edition2015-08-01Reference numberISO 13528:2015(E)BS ISO 13528:2015ISO 13528:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced
6、 or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO
7、copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 13528:2015ISO 13528:2015(E)Foreword v0 Introduction .vi1 Scope . 12 Normative references 13 Terms and definitions . 14 General principles . 44.1 Ge
8、neral requirements for statistical methods . 44.2 Basic model 54.3 General approaches for the evaluation of performance 55 Guidelines for the statistical design of proficiency testing schemes . 65.1 Introduction to the statistical design of proficiency testing schemes . 65.2 Basis of a statistical d
9、esign . 65.3 Considerations for the statistical distribution of results 75.4 Considerations for small numbers of participants 85.5 Guidelines for choosing the reporting format 86 Guidelines for the initial review of proficiency testing items and results 106.1 Homogeneity and stability of proficiency
10、 test items.106.2 Considerations for different measurement methods .116.3 Blunder removal . 116.4 Visual review of data . 116.5 Robust statistical methods 126.6 Outlier techniques for individual results. 127 Determination of the assigned value and its standard uncertainty 137.1 Choice of method of d
11、etermining the assigned value.137.2 Determining the uncertainty of the assigned value .147.3 Formulation 157.4 Certified reference material 157.5 Results from one laboratory . 167.6 Consensus value from expert laboratories 177.7 Consensus value from participant results . 187.8 Comparison of the assi
12、gned value with an independent reference value 198 Determination of criteria for evaluation of performance .208.1 Approaches for determining evaluation criteria 208.2 By perception of experts 208.3 By experience from previous rounds of a proficiency testing scheme 208.4 By use of a general model . 2
13、18.5 Using the repeatability and reproducibility standard deviations from a previous collaborative study of precision of a measurement method 228.6 From data obtained in the same round of a proficiency testing scheme .228.7 Monitoring interlaboratory agreement 239 Calculation of performance statisti
14、cs 239.1 General considerations for determining performance 239.2 Limiting the uncertainty of the assigned value 249.3 Estimates of deviation (measurement error) 259.4 z scores 269.5 z scores 279.6 Zeta scores () . 289.7 Enscores 299.8 Evaluation of participant uncertainties in testing .299.9 Combin
15、ed performance scores 30 ISO 2015 All rights reserved iiiContents PageBS ISO 13528:2015ISO 13528:2015(E)10 Graphical methods for describing performance scores 3110.1 Application of graphical methods 3110.2 Histograms of results or performance scores . 3110.3 Kernel density plots . 3210.4 Bar-plots o
16、f standardized performance scores3310.5 Youden Plot . 3310.6 Plots of repeatability standard deviations . 3410.7 Split samples . 3510.8 Graphical methods for combining performance scores over several rounds of a proficiency testing scheme . 3611 Design and analysis of qualitative proficiency testing
17、 schemes (including nominal and ordinal properties) 3711.1 Types of qualitative data . 3711.2 Statistical design . 3711.3 Assigned values for qualitative proficiency testing schemes .3811.4 Performance evaluation and scoring for qualitative proficiency testing schemes39Annex A (normative) Symbols 42
18、Annex B (normative) Homogeneity and stability of proficiency test items 44Annex C (normative) Robust analysis .52Annex D (informative) Additional Guidance on Statistical Procedures 63Annex E (informative) Illustrative Examples 67Bibliography .89iv ISO 2015 All rights reservedBS ISO 13528:2015ISO 135
19、28:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for
20、which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on al
21、l matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. Th
22、is document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or
23、 all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users
24、and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary
25、informationThe committee responsible for this document is ISO/TC 69, Applications of statistical methods, Subcommittee SC 6, Measurement methods and results.This second edition of ISO 13528 cancels and replaces the first edition (ISO 13528:2005), of which it constitutes a technical revision. This se
26、cond edition provides changes to bring the document into harmony with ISO/IEC 17043:2010, which replaced ISO Guide 43-1:1997. It follows a revised structure, to describe better the process of the design, analysis, and reporting of proficiency testing schemes. It also eliminates some procedures that
27、are no longer considered to be appropriate, and adds or revises some other sections to be consistent with ISO/IEC 17043 and to provide clarity and correct minor errors. New sections have been added for qualitative data and additional robust statistical methods. ISO 2015 All rights reserved vBS ISO 1
28、3528:2015ISO 13528:2015(E)0 Introduction0.1 The purposes of proficiency testingProficiency testing involves the use of interlaboratory comparisons to determine the performance of participants (which may be laboratories, inspection bodies, or individuals) for specific tests or measurements, and to mo
29、nitor their continuing performance. There are a number of typical purposes of proficiency testing, as described in the Introduction to ISO/IEC 17043:2010. These include the evaluation of laboratory performance, the identification of problems in laboratories, establishing effectiveness and comparabil
30、ity of test or measurement methods, the provision of additional confidence to laboratory customers, validation of uncertainty claims, and the education of participating laboratories. The statistical design and analytical techniques applied must be appropriate for the stated purpose(s).0.2 Rationale
31、for scoring in proficiency testing schemesA variety of scoring strategies is available and in use for proficiency testing. Although the detailed calculations differ, most proficiency testing schemes compare the participants deviation from an assigned value with a numerical criterion which is used to
32、 decide whether or not the deviation represents cause for concern. The strategies used for value assignment and for choosing a criterion for assessment of the participant deviations are therefore critical. In particular, it is important to consider whether the assigned value and criterion for assess
33、ing deviations should be independent of participant results, or should be derived from the results submitted. In this Standard, both strategies are provided for. However, attention is drawn to the discussion that will be found in sections 7 and 8 of the advantages and disadvantages of choosing assig
34、ned values or criteria for assessing deviations that are not derived from the participant results. It will be seen that in general, choosing assigned values and assessment criteria independently of participant results offers advantages. This is particularly the case for the criterion used to assess
35、deviations from the assigned value such as the standard deviation for proficiency assessment or an allowance for measurement error for which a consistent choice based on suitability for a particular end use of the measurement results, is especially useful.0.3 ISO 13528 and ISO/IEC 17043ISO 13528 pro
36、vides support for the implementation of ISO/IEC 17043 particularly, on the requirements for the statistical design, validation of proficiency test items, review of results, and reporting summary statistics. Annex B of ISO/IEC 17043:2010 briefly describes the general statistical methods that are used
37、 in proficiency testing schemes. This International Standard is intended to be complementary to ISO/IEC 17043, providing detailed guidance that is lacking in that document on particular statistical methods for proficiency testing.The definition of proficiency testing in ISO/IEC 17043 is repeated in
38、ISO 13528, with the Notes that describe different types of proficiency testing and the range of designs that can be used. This Standard cannot specifically cover all purposes, designs, matrices and measurands. The techniques presented in ISO 13528 are intended to be broadly applicable, especially fo
39、r newly established proficiency testing schemes. It is expected that statistical techniques used for a particular proficiency testing scheme will evolve as the scheme matures; and the scores, evaluation criteria, and graphical techniques will be refined to better serve the specific needs of a target
40、 group of participants, accreditation bodies, and regulatory authorities.ISO 13528 incorporates published guidance for the proficiency testing of chemical analytical laboratories 32but additionally includes a wider range of procedures to permit use with valid measurement methods and qualitative iden
41、tifications. This revision of ISO 13528:2005 contains most of the statistical methods and guidance from the first edition, extended as necessary by the previously referenced documents and the extended scope of ISO/IEC 17043. ISO/IEC 17043 includes proficiency testing for individuals and inspection b
42、odies, and Annex B, which includes considerations for qualitative results.This Standard includes statistical techniques that are consistent with other International Standards, particularly those of TC69 SC6, notably the ISO 5725 series of standards on Accuracy: trueness and precision. The techniques
43、 are also intended to reflect other international standards, where appropriate, and are intended to be consistent with ISO/IEC Guide 98-3 (GUM) and ISO/IEC Guide 99 (VIM).vi ISO 2015 All rights reservedBS ISO 13528:2015ISO 13528:2015(E)0.4 Statistical expertiseISO/IEC 17043:2010 requires that in ord
44、er to be competent, a proficiency testing provider shall have access to statistical expertise and shall authorize specific personnel to conduct statistical analysis. Neither ISO/IEC 17043 nor this International Standard can specify further what that necessary expertise is. For some applications an a
45、dvanced degree in statistics is useful, but usually the needs for expertise can be met by individuals with technical expertise in other areas, who are familiar with basic statistical concepts and have experience or training in the common techniques applicable to the analysis of data from proficiency
46、 testing schemes. If an individual is charged with statistical design and/or analysis, it is very important that this person has experience with interlaboratory comparisons, even if that person has an advanced degree in statistics. Conventional advanced statistical training often does not include ex
47、ercises with interlaboratory comparisons, and the unique causes of measurement error that occur in proficiency testing can seem obscure. The guidance in this International Standard cannot provide all the necessary expertise to consider all applications, and cannot replace the experience gained by wo
48、rking with interlaboratory comparisons.0.5 Computer softwareComputer software that is needed for statistical analysis of proficiency testing data can vary greatly, ranging from simple spread sheet arithmetic for small proficiency testing schemes using known reference values to sophisticated statisti
49、cal software used for statistical methods reliant on iterative calculations or other advanced numerical methods. Most of the techniques in this International Standard can be accomplished by conventional spread sheet applications, perhaps with customised routines for a particular scheme or analysis; some techniques will require computer applications that are freely available (at the time of publication of this Standard). In all cases, the users should verify the accuracy of their calculations, especially when special routines have been entered by the user
