1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-23814-8 SANS 22971:2010Edition 1ISO/TR 22971:2005Edition 1SOUTH AFRICAN NATIONAL STANDARD Accuracy (trueness and precision) of measurement
4、 methods and results Practical guidance for the use of ISO 5725-2:1994 in designing, implementing and statistically analysing interlaboratory repeatability and reproducibility results This national standard is the identical implementation of ISO/TR 22971:2005 and is adopted with the permission of th
5、e International Organization for Standardization. Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 22971:2010 Edition 1 ISO/TR 22971:2005 Edition 1 Table of changes Change No. Date Scope
6、 National foreword This South African standard was approved by National Committee SABS TC 169, Applications of statistical methods, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This SANS document was published in March 2010. Refer
7、ence numberISO/TR 22971:2005(E)ISO 2005TECHNICAL REPORT ISO/TR22971First edition2005-01-15Accuracy (trueness and precision) of measurement methods and results Practical guidance for the use of ISO 5725-2:1994 in designing, implementing and statistically analysing interlaboratory repeatability and re
8、producibility results Exactitude (justesse et fidlit) des rsultats et mthodes de mesure Lignes directrices pratiques pour lutilisation de lISO 5725-2:1994 pour la conception, la mise en uvre et lanalyse statistique des rsultats de rptabilit et de reproductibilit interlaboratoires SANS 22971:2010This
9、 s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO/TR 22971:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the ty
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14、witzerland ii ISO 2005 All rights reservedSANS 22971:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO/TR 22971:2005(E) ISO 2005 All rights reserved iiiContents Page Foreword. v Introduction vii 1 Scope 1 2 Organization of an inter-labo
15、ratory programme 1 2.1 Requirements for a precision experiment 1 2.2 The responsibilities of the personnel involved in a precision experiment. 1 3 Critical examination of the data. 3 3.1 Description of the data . 3 3.2 Tests for outliers . 7 3.3 Conclusions. 9 4 Estimation of repeatability and repro
16、ducibility standard deviations 11 4.1 Analysis of variance . 11 4.2 Description of the model 11 4.3 Examples 13 4.4 Use of repeatability and reproducibility limits.15 5 Worked examples using statistical software . 16 5.1 General. 16 5.2 Determination of sulfur content in coal 16 5.3 Thermometric tit
17、ration of creosote oil 23 Annex A (normative) Symbols and abbreviations 30 Bibliography . 33 SANS 22971:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO/TR 22971:2005(E) iv ISO 2005 All rights reservedForeword ISO (the International Or
18、ganization 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 which a technical committee has been establ
19、ished 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 all matters of electrotechnical standardizati
20、on. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
21、 Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In exceptional circumstances, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, fo
22、r example), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does not have to be reviewed until the data it provides are considered to be no longer valid or useful. Attention is drawn to the p
23、ossibility 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 all such patent rights. ISO/TR 22971 was prepared by Technical Committee ISO/TC 69, Applications of statistical methods, Subcommittee SC 6, Measurement
24、methods and results. SANS 22971:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO/TR 22971:2005(E) ISO 2005 All rights reserved vIntroduction ISO 5725 consists of six parts, the general structure of which is shown in Figure 1. ISO 5725-
25、2 was developed as a guidance document for ISO Technical Committees and other organizations responsible for undertaking inter-laboratory studies for characterizing the variability of standard measurement methods. Two measures of variability, repeatability and reproducibility, are accepted in many di
26、sciplines as representative of data encountered in measurement processes. Repeatability refers to the variability among measurements made on nominally identical samples or materials under identical circumstances. It is recognized that, because of unknown or uncontrollable factors which influence the
27、 measurement process, repeated measurements will usually not agree. The extent of this variability can be expressed by a standard deviation, called the repeatability standard deviation, of the results of within-laboratory comparisons. Reproducibility refers to the variability among measurements made
28、 on identical samples or materials under differing conditions by different laboratories following the same standard measurement method. Reproducibility includes effects caused by differences among instruments, reagents, operators, laboratories, and environmental conditions. The variability of result
29、s under these conditions may be described by a standard deviation called the reproducibility standard deviation. This guidance document is divided into four clauses in addition to the Scope (Clause 1): Clause 2, Organization of an inter-laboratory programme, deals with the organization of the inter-
30、laboratory test and covers the roles of the executive officer, laboratory personnel, and statistician in preparing for and administering the test; the choice of materials and levels of interest for the test; and the selection of laboratories. It also describes how the number of replicate measurement
31、s (to be made on each sample) is to be statistically treated and the manner in which the resulting data are to be reported. Clause 3, Critical examination of the data, deals with data using graphical and numerical procedures. Guidance is given as to when data are anomalous, i.e. if they are inconsis
32、tent with other data from the study, and for outlier tests that are used to identify the presence or absence of anomalous data. Clause 4, Estimation of repeatability and reproducibility standard deviations, deals with the estimation and interpretation of repeatability and reproducibility standard de
33、viations. Also included is a comparison of the relative contributions of the repeatability and reproducibility standard deviations to the total variability of the test method. Clause 5, Worked examples using statistical software, deals with worked examples that highlight various techniques that can
34、be used. It is recommended that this guidance document be read in conjunction with ISO 5725-2 and should not be used as a replacement for ISO 5725-2. SANS 22971:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO/TR 22971:2005(E) vi ISO 2
35、005 All rights reservedFigure 1 Structure of ISO 5725 Application of a standardized test method to the analyses of a sample or product in different laboratories SANS 22971:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .TECHNICAL REPORT I
36、SO/TR 22971:2005(E) ISO 2005 All rights reserved 1Accuracy (trueness and precision) of measurement methods and results Practical guidance for the use of ISO 5725-2:1994 in designing, implementing and statistically analysing interlaboratory repeatability and reproducibility results 1 Scope This Techn
37、ical Report provides users with practical guidance to the use of ISO 5725-2:1994 and presents simplified step-by-step procedures for the design, implementation, and statistical analysis of inter-laboratory studies for assessing the variability of a standard measurement method and on the determinatio
38、n of repeatability and reproducibility of data obtained in inter-laboratory testing. 2 Organization of an inter-laboratory programme 2.1 Requirements for a precision experiment The whole experiment is organized a) to provide a complete set of results for: pLabnumber of laboratories demonstrating tha
39、t the test procedure is well controlled and for quantifying the observed scatter, estimated by the reproducibility; NOTE The symbol pLabused in this Technical Report has the same meaning as the symbol p used in ISO 5725-2:1994. The change was made to clearly distinguish this symbol from the symbol,
40、P, used for “probability”. The lowercase and uppercase Ps are sometimes difficult to distinguish, particularly as subscripts. q number of samples or products representing different levels of results or performance. A minimum value for q is two, but from five to ten is more appropriate for demonstrat
41、ing that the test procedure is able to discriminate correctly between levels; n number of replications cell demonstrating that the test procedure is well controlled within a single laboratory. When the number of laboratories and of levels is sufficient, at least two determinations are required; b) t
42、o analyse statistically (see Clauses 2 and 3) a table of results reported by pLablaboratories analysing q samples, tested n times under conditions of repeatability. The table of the results submitted to the executive officer is shown in Table 1 (see ISO 5725-2:1994, 7.2.8). 2.2 The responsibilities
43、of the personnel involved in a precision experiment 2.2.1 General An inter-laboratory programme is very expensive, both in terms of its co-ordination and its participation. Hence, the performance testing should be well co-ordinated and planned. In any inter-laboratory programme, it is necessary to c
44、onsider three types of activity as shown in Figure 2. SANS 22971:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO/TR 22971:2005(E) 2 ISO 2005 All rights reservedFigure 2 The responsibilities of executive functions 2.2.2 Executive offic
45、er The executive officers main tasks are to organize the inter-laboratory programme, with the advice of the statistician for the construction of the experimental design; to co-ordinate the progress; to state the conclusions. The duties of the executive officer may be undertaken by more than one pers
46、on. However, only one person should be responsible for the entire programme. The executive officer should be familiar with the standard method, but should not participate in the measurement process. 2.2.3 Laboratory The laboratory personnel should be fully experienced with the test measurement metho
47、d. The laboratory shall undertake the analysis, adhering to the test procedures received from the executive officer. Any comments by the laboratory on the use of the test method should be reported to the executive officer. However, the procedures carried out by the laboratory should be those provide
48、d by the executive officer. The laboratory shall comply with any requirements prescribed by the executive officer, including storage of the samples; date and order of carrying out the analysis. The laboratory shall provide the executive officer with the results of analysis in a manner prescribed by
49、the executive officer. 2.2.4 Statistician The statistician shall receive from the executive officer the raw data obtained using the stated method and as reported in Table 1. SANS 22971:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO/TR 22971:2005(E) ISO 2005 All rights reserved 3The statistician shall examine the data and apply any statistical test, preferentially the tests described in ISO 5725-2, to identify potential outliers. Sta
