ISO-20988-2007.pdf
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1、 Reference number ISO 20988:2007(E) ISO 2007 INTERNATIONAL STANDARD ISO 20988 First edition 2007-06-15 Air quality Guidelines for estimating measurement uncertainty Qualit de lair Lignes directrices pour estimer lincertitude de mesure Copyright International Organization for Standardization Provided
2、 by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 04:33:11 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20988:2007(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes
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5、s been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2007 All rights reserved. Unless otherwise specified, no par
6、t of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 5
7、6 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 2007 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DA
8、WSON, DAVIS Not for Resale, 07/03/2007 04:33:11 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20988:2007(E) ISO 2007 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references. 1 3 Terms and definitions. 1 4 Symbols and abbrevi
9、ated terms . 5 5 Basic concepts 6 5.1 Outline 6 5.2 Measurement uncertainty 9 5.3 Correction for systematic effects 10 5.4 Provision of input data. 11 6 Problem specification. 13 6.1 Objectives 13 6.2 Measurement. 13 6.3 Uncertainty parameters 15 6.4 Input data. 15 6.4.1 General. 15 6.4.2 Assessment
10、 of representativeness 16 6.5 Effects not described by series of observations. 17 7 Statistical analysis 18 7.1 Objectives 18 7.2 Indirect approach 19 7.3 Direct approach. 21 7.4 Statistical validity 22 8 Estimation of variances and covariances 23 8.1 General. 23 8.2 Variance estimates of Type A 23
11、8.3 Variance estimates of Type B 23 8.4 Estimation of covariances . 24 9 Evaluation of uncertainty parameters 25 9.1 Objective 25 9.2 Combined standard uncertainty 25 9.3 Expanded uncertainty 26 9.3.1 General. 26 9.3.2 Expanded uncertainty of results exhibiting a Gaussian distribution 27 10 Reportin
12、g. 28 Annex A (informative) Testing a coverage probability. 30 Annex B (informative) Type A evaluation methods for experimental designs A1 to A8. 34 Annex C (informative) Examples 49 Bibliography. 81 Copyright International Organization for Standardization Provided by IHS under license with ISO Lice
13、nsee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 04:33:11 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 20988:2007(E) iv ISO 2007 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federatio
14、n 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 established has the right to be represented on that committee.
15、 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 standardization. International Standards are drafted in accordance wi
16、th 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. Publication as an International Standard requires appro
17、val by at least 75 % of the member bodies casting a vote. 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 20988 was prepared by Technical Committ
18、ee ISO/TC 146, Air quality, Subcommittee SC 4, General aspects. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 04:33:11 MDTNo reproduction or networking permitted without
19、 license from IHS -,-,- ISO 20988:2007(E) ISO 2007 All rights reserved v Introduction The general concept of uncertainty estimation is described in the Guide to the Expression of Uncertainty in Measurement (GUM). Practical considerations of the GUM are focussed on evaluation of series of unbiased ob
20、servations. In air quality measurements, series of observations may rarely be considered unbiased due to the presence of random effects not varying throughout a series of observations. This International Standard supports evaluation of random effects causing variation or bias in series of observatio
21、ns for the purpose of uncertainty estimation. Appropriate data may be collected in experimental designs providing comparison with reference material, or with reference instruments, or with independent measurements of the same type. In provision of experimental data for uncertainty estimation, it is
22、important to ensure representativeness for variations and bias occurring in intended use of the method of measurement. Generic guidance and statistical procedures presented by this International Standard are addressed to technical experts of air quality measurement, acting, e.g. in standardization,
23、validation or documentation of methods of measurement in ambient air, indoor air, stationary source emissions, workplace atmospheres or meteorology. This International Standard does not provide comprehensive information on planning and execution of experimental designs to be evaluated for the purpos
24、e of uncertainty estimation. Uncertainties of results of measurement caused by incomplete time-coverage of measurement data are not considered in this document, but in ISO 112222. Uncertainties of results of measurement induced by incomplete spatial coverage by measurement data are not considered in
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