1、DRAFT FOR DEVELOPMENT DD ISO/TS 21749:2005 Measurement and uncertainty for metrological applications Repeated measurements and nested experiments ICS 17.020 DD ISO/TS 21749:2005 This Draft for Development was published under the authority of the Standards Policy and Strategy Committee on 16 May 2005
2、 BSI 16 May 2005 ISBN 0 580 45979 9 National foreword This Draft for Development reproduces verbatim ISO/TS 21749:2005. This publication is not to be regarded as a British Standard. It is being issued in the Draft for Development Series of publications and is of a provisional nature because of the l
3、imited duration of the International Technical Specification. It should be applied on this provisional basis, so that information and experience of its practical application may be obtained. Comments arising from the use of this Draft for Development are requested so that UK experience can be report
4、ed to the international organization responsible for the Technical Specification. A review of this publication will be initiated not later than 3 years after its publication by the international organization so that a decision can be taken on its status at the end of its 3-year life. Notification of
5、 the start of the review period will be made in an announcement in the appropriate issue of Update Standards. According to the replies received by the end of the review period, the responsible BSI Committee will decide whether to support the conversion into an international standard, to extend the l
6、ife of the Technical Specification for another 3 years or to withdraw it. Comments should be sent in writing to the Secretary of BSI Technical Committee SS/6, Precision of test methods, at British Standards House, 389 Chiswick High Road, London W4 4AL, giving the document reference and clause number
7、 and proposing, where possible, an appropriate revision of the text. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the B
8、SI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. Summary of pages This document comprises a front cover, an inside front cover, the ISO/TS title page, pages ii to
9、v, a blank page, pages 1 to 38, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO/TS 21749:2005(E)TECHNICAL NOITACIFICEPS ISO/TS 29471
10、 tide tsriFino -500251-20 Measurement and uncertainty for metrological applications Repeated measurements and nested experiments Incertitude de mesure pour les applications en mtrologie Mesures rptes et expriences embotes Referecne unbmer OSI/TS 02:94712)E(50TECHNICAL SPECIFICATION ISO/TS 21749 Firs
11、t edition 2005-02-15 erusaeMnemt au dnnrecniatty for lortemgoa lacipitacilpsno eR etaepd erusaememetsen dna stnd xepenemirts cnIretutisem ed edrue pruo sel palpciitasno en mrtlooseM eigruse rtpse xe tepriecnse etobmse DDISO/TS21749:2005DPlcsid Fremia ihTs PDF file mya ctnoian emdebt dedyfepcaes. In
12、ccacnadrow eitA hebods licnesilop gnic,y tihs file mirp eb yatnde iv roweb detu slahl ton ide ebtlnu deess teh typfecaes wihce era hml era deddebicsnede ti dna onstlalde t noeh comuptfrep reromign tide ehtin.g In wodlnidaot gnihs fil,e trapise atpecc tiereht nser ehnopsiiblity fo nto ifnriigngn Aebo
13、ds licnesilop gnic.y ehT ISO tneClar Secrteirata caceptl on siibality in this .aera Ai ebods a tedarmfo kra Aebod SystemI snctaropro.de teDials fo teh sfotwcudorp erats sut deo crtaee tihs PDF file cna f ebi dnuon tlareneG eh Ifnler oatit evt oeh file; tP ehDc-Frtaeino marapteres wtpo ereimizf deirp
14、 rotni.gn Evc yresah era t neebakt nesne ot erutah teh fili es siutlbaf eosu rI yb eSO memdob rebeis. In tlnu ehikletneve y ttah lborp aem lertait gno it is f,dnuo plsaee ifnrom ttneC ehlar Secterirata ta teh serddaig sleb nevwo. ii DDISO/TS21749:2005 iiiContents Page Foreword iv Introduction.v 1 Sc
15、ope1 2 Normative references1 3 Terms and definitions .2 4 Statistical methods of uncertainty evaluation3 4.1 Approach of the Guide to the expression of uncertainty of measurement.3 4.2 Check standards .4 4.3 Steps in uncertainty evaluation .5 4.4 Examples in this Technical Specification.6 5 Type A e
16、valuation of uncertainty.6 5.1 General .6 5.2 Role of time in Type A evaluation of uncertainty.7 5.3 Measurement configuration .14 5.4 Material inhomogeneity 16 5.5 Bias due to measurement configurations 17 6 Type B evaluation of uncertainty.26 7 Propagation of uncertainty.27 7.1 General .27 7.2 For
17、mulae for functions of a single variable28 7.3 Formulae for functions of two variables.28 8 Example Type A evaluation of uncertainty from a gauge study30 8.1 Purpose and background .30 8.2 Data collection and check standards30 8.3 Analysis of repeatability, day-to-day and long-term effects.31 8.4 Pr
18、obe bias 31 8.5 Wiring bias .33 8.6 Uncertainty calculation.35 Annex A (normative) Symbols.37 Bibliography38 DDISO/TS21749:2005iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Intern
19、ational Standards is 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
20、 ISO, also take part 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
21、 committees is to prepare 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 other circumstances
22、, particularly when there is an urgent market requirement for such documents, a technical committee may decide to publish other types of normative document: an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in an ISO working group and is accepted for
23、 publication if it is approved by more than 50 % of the members of the parent committee casting a vote; an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical committee and is accepted for publication if it is approved by 2/3 of the members of the committe
24、e casting a vote. An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is confirmed, it is reviewed again after a further three years, at which
25、 time it must either be transformed into an International Standard or be withdrawn. 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 patent rights. ISO/TS 21749 was
26、prepared by Technical Committee ISO/TC 69, Applications of statistical methods, Subcommittee SC 6, Measurement methods and results. DDISO/TS21749:2005 vIntroduction Test, calibration and other laboratories are frequently required to report the results of measurements and the associated uncertainties
27、. Evaluation of uncertainty is an on-going process that can consume time and resources. In particular, there are many tests and other operations carried out by laboratories where two or three sources of uncertainty are involved. Following the approach in the Guide to the expression of uncertainty of
28、 measurement (GUM) to combining components of uncertainty, this document focuses on using the analysis of variance (ANOVA) for estimating individual components, particularly those based on Type A (statistical) evaluations. An experiment is designed by the laboratory to enable an adequate number of m
29、easurements to be made, the analysis of which will permit the separation of the uncertainty components. The experiment, in terms of design and execution, and the subsequent analysis and uncertainty evaluation, require familiarity with data analysis techniques, particularly statistical analysis. Ther
30、efore, it is important for laboratory personnel to be aware of the resources required and to plan the necessary data collection and analysis. In this Technical Specification, the uncertainty components based on Type A evaluations can be estimated from statistical analysis of repeated measurements, f
31、rom instruments, test items or check standards. A purpose of this Technical Specification is to provide guidance on the evaluation of the uncertainties associated with the measurement of test items, for instance as part of ongoing manufacturing inspection. Such uncertainties contain contributions fr
32、om the measurement process itself and from the variability of the manufacturing process. Both types of contribution include those from operators, environmental conditions and other effects. In order to assist in separating the effects of the measurement process and manufacturing variability, measure
33、ments of check standards are used to provide data on the measurement process itself. Such measurements are nominally identical to those made on the test items. In particular, measurements on check standards are used to help identify time-dependent effects, so that such effects can be evaluated and c
34、ontrasted with a database of check standard measurements. These standards are also useful in helping to control the bias and long-term drift of the process once a baseline for these quantities has been established from historical data. Clause 4 briefly describes the statistical methods of uncertaint
35、y evaluation including the approach recommended in the GUM, the use of check standards, the steps in uncertainty evaluation and the examples in this Technical Specification. Clause 5, the main part of this Technical Specification, discusses the Type A evaluations. Nested designs in ANOVA are used in
36、 dealing with time-dependent sources of uncertainty. Other sources such as those from the measurement configuration, material inhomogeneity, and the bias due to measurement configurations and related uncertainty analyses are discussed. Type B (non-statistical) evaluations of uncertainty are discusse
37、d for completeness in Clause 6. The law of propagation of uncertainty described in the GUM has been widely used. Clause 7 provides formulae obtained by applying this law to certain functions of one and two variables. In Clause 8, as an example, a Type A evaluation of uncertainty for a gauge study is
38、 discussed, where uncertainty components from various sources are obtained. Annex A lists the statistical symbols used in this Technical Specification. DDISO/TS21749:2005blankTECINHCAICEPS LFICATION IS/OTS :94712(5002)EMeasurement and uncertainty for metrological applications Repeated measurements a
39、nd nested experiments 1 Scope This Technical Specification follows the approach taken in the Guide to the expression of the uncertainty of measurement ( GUM) and establishes the basic structure for stating and combining components of uncertainty. To this basic structure, it adds a statistical framew
40、ork using the analysis of variance (ANOVA) for estimating individual components, particularly those classified as Type A evaluations of uncertainty, i.e. based on the use of statistical methods. A short description of Type B evaluations of uncertainty (non-statistical) is included for completeness.
41、This Technical Specification covers experimental situations where the components of uncertainty can be estimated from statistical analysis of repeated measurements, instruments, test items or check standards. It provides methods for obtaining uncertainties from single-, two- and three-level nested d
42、esigns only. More complicated experimental situations where, for example, there is interaction between operator effects and instrument effects or a cross effect, are not covered. This Technical Specification is not applicable to measurements that cannot be replicated, such as destructive measurement
43、s or measurements on dynamically varying systems (such as fluid flow, electronic currents or telecommunications systems). It is not particularly directed to the certification of reference materials (particularly chemical substances) and to calibrations where artefacts are compared using a scheme kno
44、wn as a “weighing design”. For certification of reference materials, see ISO Guide 35 14 . When results from interlaboratory studies can be used, techniques are presented in the companion guide ISO/TS 21748 15 . The main difference between ISO/TS 21748 and this Technical Specification is that the IS
45、O/TS 21748 is concerned with reproducibility data (with the inevitable repeatability effects), whereas this Technical Specification concentrates on repeatability data and the use of the analysis of variance for its treatment. This Technical Specification is applicable to a wide variety of measuremen
46、ts, for example, lengths, angles, voltages, resistances, masses and densities. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the ref
47、erenced document (including any amendments) applies. ISO 3534-1:1993, Statistics Vocabulary and symbols Part 1: Probability and general statistical terms ISO 3534-3:1999, Statistics Vocabulary and symbols Part 3: Design of experiments ISO 5725-1, Accuracy (trueness and precision) of measurement meth
48、ods and results Part 1: General principles and definitions ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method DDISO/TS21749:20051 ISO 5725-3, Accuracy (truen
49、ess and precision) of measurement methods and results Part 3: Intermediate measures of the precision of a standard measurement method ISO 5725-4, Accuracy (trueness and precision) of measurement methods and results Part 4: Basic methods for the determination of the trueness of a standard measurement method ISO 5725-5, Accuracy (trueness and precision) of measurement methods and results Part 5: Alternative methods for the determination of the precision of a
