1、 Reference number ISO/TR 9272:2005(E) ISO 2005TECHNICAL REPORT ISO/TR 9272 Second edition 2005-07-15 Rubber and rubber products Determination of precision for test method standards Caoutchouc et produits en caoutchouc valuation de la fidlit des mthodes dessai normalises ISO/TR 9272:2005(E) PDF discl
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6、he requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2005 All rights reservedISO/TR 9272:2005(E) ISO 2005 All rights reserved iiiContents Page Foreword. v Introduction
7、 . vi 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 3.1 General. 1 3.2 ISO 5725 terms 2 3.3 Required terms not in ISO 5725 4 4 Field of application . 6 4.1 General background. 6 4.2 Defining repeatability and reproducibility 7 5 Precision determination: Level 1 precision and leve
8、l 2 precision. 8 5.1 Level 1 precision. 8 5.2 Level 2 precision. 8 5.3 Types of level 1 and level 2 precision. 8 6 Steps in organizing an interlaboratory test programme. 9 7 Overview of level 1 precision analysis procedure 11 7.1 Analysis operation sequence 11 7.2 Background on outliers 12 7.3 Outli
9、er appearance patterns 12 7.4 Sequential review of outliers . 12 8 Level 1 precision: Analysis step 1 13 8.1 Preliminary numerical and graphical data review . 13 8.2 Graphical review of cell values . 13 8.3 Calculation of precision for original database 14 8.4 Detection of outliers at the 5 % signif
10、icance level using h and k statistics . 14 8.5 Generation of revision 1 database using outlier option 1 or 2 15 8.6 Revision 1 (R1) database tables 15 9 Level 1 precision: Analysis step 2 15 9.1 Detection of outliers at the 2 % significance level using h and k statistics . 15 9.2 Generation of revis
11、ion 2 database using outlier option 1 or 2 15 10 Level 1 precision: Analysis step 3 Final precision results 16 11 Level 2 precision: Analysis of results obtained when testing carbon blacks 16 11.1 Background on level 2 precision 16 11.2 Data review and calculations. 17 11.3 Expressing the precision
12、determined for carbon black testing 17 12 Format for level 1 and level 2 precision-data table and precision clause in test method standards. 18 12.1 Precision-data table 18 12.2 Precision clause 18 12.3 Report on the precision determination ITP 20 Annex A (normative) Calculating the h and k consiste
13、ncy statistics. 25 A.1 General background. 25 A.2 Defining and calculating the h statistic 25 A.3 Defining and calculating the k-statistic 26 ISO/TR 9272:2005(E) iv ISO 2005 All rights reservedA.4 Identification of outliers using the critical h and k values 27 Annex B (normative) Spreadsheet calcula
14、tion formulae for precision parameters Recommended spreadsheet table layout and data calculation sequence . 29 B.1 Calculation formulae. 29 B.2 Table layout for spreadsheet calculations .30 B.3 Sequence of database calculations for precision . 33 Annex C (normative) Procedure for calculating replace
15、ment values for deleted outliers 35 C.1 Introduction . 35 C.2 The replacement procedure. 35 C.3 Outlier replacement categories . 36 C.4 PRs for outliers at 5 % significance level . 36 C.5 DRs for outliers at 5 % significance level. 37 C.6 PRs for outliers at 2 % significance level . 37 C.7 DRs for o
16、utliers at 2 % significance level. 38 Annex D (normative) An example of general precision determination Mooney viscosity testing . 39 D.1 Introduction . 39 D.2 Organization of the Mooney example precision determination . 40 D.3 Part 1: Level 1 analysis Option 2: Outlier replacement 40 D.4 Part 2: Le
17、vel 1 precision analysis Option 1: Outlier deletion 49 Annex E (informative) Background on ISO 5725 and new developments in precision determination. 76 E.1 Elements of ISO 5725 76 E.2 Elements of this TC 45 precision standard 76 Bibliography . 78 ISO/TR 9272:2005(E) ISO 2005 All rights reserved vFor
18、eword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is
19、normally carried out through ISO technical committees. Each member body interested in a subject for 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
20、in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. 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 pre
21、pare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In exceptional circumstances, when a techni
22、cal committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for 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
23、 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 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 all such
24、patent rights. ISO/TR 9272 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis. This second edition cancels and replaces the first edition (ISO/TR 9272:1986), which has been technically revised. ISO/TR 9272:2005(E) vi ISO 2005 All rights
25、 reservedIntroduction The primary precision standard for ISO test method standards is ISO 5725, a generic standard that presents the fundamental statistical approach and calculation algorithms for determining repeatability and reproducibility precision as well as accuracy and a concept related to bi
26、as called trueness. However there are certain parts of ISO 5725 that are not compatible with precision determination in the rubber manufacturing and carbon black industries over the past four decades. two major problems exist: a) strict adherence to ISO 5725 conflicts with the operational procedures
27、 and the past history of testing as conducted in these two industries and b) ISO 5725 does not address certain requirements that are unique to rubber and carbon black testing. Thus although ISO 5725 is necessary as a foundation document for this Technical Report and is used as such, it is not suffic
28、ient for the needs of TC 45. This Technical Report replaces ISO/TR 9272, an interim document that has been used for guidance on precision determination since 1986. This new edition of the Technical Report has a more comprehensive approach to the overriding issue with precision determination over the
29、 past several decades the discovery that the reproducibility (between-laboratory variation) of many test methods is quite large. The existence of very poor between-laboratory agreement for many fundamental test methods in the industry has been the subject of much discussion and consternation. Experi
30、ence has shown that poor reproducibility is most often caused by only a small number (percentage) of the laboratories that may be designated outlier laboratories. This new edition of ISO/TR 9272 describes a “robust” analysis approach that eliminates or substantially reduces the influence of outliers
31、. See Annex E for a more detailed discussion of these issues and additional background on ISO 5725. Five annexes are presented. These serve as supplements to the main body of the Technical Report. They are in addition to the terminology section proper. Annex A defines the Mandel h and k statistics,
32、illustrates how they are calculated and gives tables of critical h and k values. Annex B lists the calculation formulae for repeatability and reproducibility. It also describes how to generate and use six tables that are required for a spreadsheet precision analysis. Annex C outlines the procedure f
33、or calculating replacement values for outliers that have been rejected by h and k value analysis. Outlier replacement rather than deletion is an option that may be used for precision determination with a minimum number of laboratories and/or materials. Annex D is an example of a typical general prec
34、ision determination programme for Mooney viscosity testing. It shows how a precision database is reviewed for outliers, using both the h and the k statistics, and illustrates some of the problems with outlier identification and removal as described in ISO 5725-2. Annex E presents some background on
35、ISO 5725, robust analysis and other issues related to precision determination. Annex E is given mainly as background information that is important for a full understanding of precision determination. Annexes A, B, and C contain detailed instructions and procedures needed to perform the operations ca
36、lled for in various parts of this Technical Report. The use of these annexes in this capacity avoids long sections of involved instruction in the main body of the Technical Report, thus allowing better understanding of the concepts involved in the determination of precision. TECHNICAL REPORT ISO/TR
37、9272:2005(E) ISO 2005 All rights reserved 1Rubber and rubber products Determination of precision for test method standards 1 Scope This Technical Report presents guidelines for determining, by means of interlaboratory test programmes (ITPs), precision for test method standards used in the rubber man
38、ufacturing and the carbon black industries. It uses the basic one-way analysis of variance calculation algorithms of ISO 5725 and as many of the terms and definitions of ISO 5725 as possible that do not conflict with the past history and procedures for precision determination in these two industries
39、. Although bias is not determined in this Technical Report, it is an essential concept in understanding precision determination. The ISO 5725 concepts of accuracy and trueness are not determined in this Technical Report. Two precision determination methods are given that are described as “robust” st
40、atistical procedures that attempt to eliminate or substantially decrease the influence of outliers. The first is a “level 1 precision” procedure intended for all test methods in the rubber manufacturing industry and the second is a specific variation of the general precision procedure, designated “l
41、evel 2 precision”, that applies to carbon black testing. Both of these use the same uniform level experimental design and the Mandel h and k statistics to review the precision database for potential outliers. However, they use slight modifications in the procedure for rejecting incompatible data val
42、ues as outliers. The “level 2 precision” procedure is specific as to the number of replicates per database cell or material-laboratory combination. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition
43、 cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3534-1, Statistics Vocabulary and symbols Part 1: Probability and general statistical terms ISO 5725 (all parts), Accuracy (trueness and precision) of measurement methods and
44、 results 3 Terms and definitions 3.1 General For the purposes of this document, the terms and definitions given in 3.3 apply, together with those in ISO 5725 with modifications in 3.2. Additional terms concerning certain types of precision can be found in 5.3. Better understanding can be gained by g
45、iving these definitions, which relate to the nature of the material to be tested, in that subclause. ISO/TR 9272:2005(E) 2 ISO 2005 All rights reserved3.2 ISO 5725 terms Terms defined in ISO 5725, usually those from ISO 3534-1, are used when: a) their definition does not conflict with the procedures
46、 required for a comprehensive treatment of precision determination for TC 45 test method standards, and b) when they are adequate to the task of giving definitions that are informative and promote understanding. In this subclause, some additional notes have been added to the ISO 5725 term definition
47、s to give greater insight into precision determination for TC 45 test methods. 3.2.1 accepted reference value value that serves as an agreed-upon reference for comparison and which is derived as: a) a theoretical or established value, based on scientific principles; b) an assigned or certified value
48、, based on experimental work of some national or international organization; c) a consensus or certified value, based on collaborative experimental work under the auspices of a scientific or engineering group; d) when a), b) and c) are not available, the expectation of the (measured) quantity, i.e.
49、the mean of a specified population of measurements. 3.2.2 test result value of a characteristic obtained by carrying out a specified test method NOTE The test method should specify that one or a number of individual measurements, determinations or observations be made and their average or another appropriate function (median or other) be reported as the test result. It may also require standard corrections to be applied, such as correction of gas volumes, etc. 3.2.3 accuracy closeness of agreement between a test result
