EN ISO 20988:2007
(Main)Air quality - Guidelines for estimating measurement uncertainty (ISO 20988:2007)
Air quality - Guidelines for estimating measurement uncertainty (ISO 20988:2007)
ISO 20988:2007 provides comprehensive guidance and specific statistical procedures for uncertainty estimation in air quality measurements including measurements of ambient air, stationary source emissions, indoor air, workplace atmospheres and meteorology. It applies the general recommendations of the Guide to the Expression of Uncertainty in Measurement (GUM) to boundary conditions met in air quality measurement. The boundary conditions considered include measurands varying rapidly in time, as well as the presence of bias in a series of observations obtained under conditions of intended use of methods of air quality measurement.
The methods of measurement considered comprise methods corrected for systematic effects by repeated observation of reference materials, methods calibrated by paired measurement with a reference method, methods not corrected for systematic effects because they are unbiased by design, and methods not corrected for systematic effects in intended use deliberately taking into account a bias.
Experimental data for uncertainty estimation can be provided either by a single experimental design in a direct approach or by a combination of different experimental designs in an indirect approach.
Luftbeschaffenheit - Leitlinien zur Schätzung der Messunsicherheit (ISO 20988:2007)
Diese Internationale Norm stellt eine umfassende Anleitung und konkrete statistische Verfahren zur Ermittlung der Unsicherheit von Messungen der Luftbeschaffenheit bereit. Dies schließt Messungen der Außenluft, der Emissionen aus stationären Quellen, der Innenraumluft, der Luft am Arbeitsplatz und der Meteorologie ein. Diese Internationale Norm wendet die allgemeinen Empfehlungen des Leitfadens zur Angabe der Unsicherheit beim Messen (GUM) für die bei Messungen der Luftbeschaffenheit vorliegenden Randbedingungen an. Zu den betrachteten Randbedingungen gehören Messgrößen mit schnellen zeitlichen Änderungen und das Auftreten von systematischen Abweichungen in Beobachtungsreihen, die unter den Bedingungen der vorgesehenen Anwendung des Verfahrens zur Messung der Luftbeschaffenheit gewonnen werden.
Zu den betrachteten Messverfahren zählen
Verfahren mit einer Korrektion bezüglich systematischer Einflüsse durch mehrmalige Beobachtung von Referenzmaterialien,
Verfahren mit einer Kalibrierung auf der Basis von Vergleichsmessungen mit einem Referenzverfahren,
Verfahren ohne Korrektion bezüglich systematischer Abweichungen, da sie auf Grund ihrer Gestaltung keine systematischen Abweichungen aufweisen, und
Verfahren ohne Korrektion bezüglich systematischer Abweichungen bei der vorgesehenen Anwendung, bei denen die systematischen Abweichungen bewusst zugelassen werden.
Die experimentellen Daten zur Unsicherheitsermittlung können entweder durch ein einzelnes Experiment auf der Basis eines direkten Ansatzes oder durch Kombination verschiedener Experimente auf der Basis eines indirekten Ansatzes geliefert werden.
Qualité de l'air - Lignes directrices pour estimer l'incertitude de mesure (ISO 20988:2007)
L'ISO 20988:2007 fournit un guide étendu et des modes opératoires statistiques spécifiques pour établir une estimation de l'incertitude dans le cadre des mesurages de la qualité de l'air, y compris les mesurages de l'air ambiant, de l'air à l'intérieur des bâtiments, des émissions de sources fixes, des ambiances de travail ou de la météorologie. Elle applique les recommandations générales du Guide pour l'expression de l'incertitude de mesure (GUM) aux conditions limites rencontrées dans le mesurage de la qualité de l'air. Les conditions limites prises en considération incluent des mesurandes qui varient rapidement avec le temps ainsi que la présence de biais dans des séries d'observations recueillies dans les conditions d'utilisation normale des méthodes de mesurage de la qualité de l'air.
Les méthodes de mesurage considérées incluent des méthodes corrigées en termes d'effets systématiques par des observations répétées de matériaux de référence, des méthodes étalonnées par mesurage par paires avec une méthode de référence, des méthodes non corrigées d'effets systématiques parce qu'elles ne sont pas biaisées par conception, et des méthodes non corrigées d'effets systématiques dans l'utilisation prévue et qui tiennent systématiquement compte d'un biais.
Les données expérimentales pour l'estimation de l'incertitude peuvent être fournies soit par un seul programme expérimental en approche directe, soit par une combinaison de programmes expérimentaux en approche indirecte.
Kakovost zraka - Smernice za ocenjevanje merilne negotovosti (ISO 20988:2007)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2008
Kakovost zraka - Smernice za ocenjevanje merilne negotovosti (ISO 20988:2007)
Air quality - Guidelines for estimating measurement uncertainty (ISO 20988:2007)
Luftbeschaffenheit - Leitlinien zur Schätzung der Messunsicherheit (ISO 20988:2007)
Qualité de l'air - Lignes directrices pour estimer l'incertitude de mesure (ISO 20988:2007)
Ta slovenski standard je istoveten z: EN ISO 20988:2007
ICS:
13.040.01 Kakovost zraka na splošno Air quality in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN ISO 20988
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2007
ICS 13.040.01
English Version
Air quality - Guidelines for estimating measurement uncertainty
(ISO 20988:2007)
Qualité de l'air - Lignes directrices pour estimer l'incertitude Luftbeschaffenheit - Leitlinien zur Schätzung der
de mesure (ISO 20988:2007) Messunsicherheit (ISO 20988:2007)
This European Standard was approved by CEN on 9 June 2007.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20988:2007: E
worldwide for CEN national Members.
Foreword
This document (EN ISO 20988:2007) has been prepared by Technical Committee ISO/TC 146
"Air quality" in collaboration with Technical Committee CEN/TC 264 "Air quality", the secretariat
of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by December 2007, and conflicting national
standards shall be withdrawn at the latest by December 2007.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United
Kingdom.
Endorsement notice
The text of ISO 20988:2007 has been approved by CEN as EN ISO 20988:2007 without any
modifications.
INTERNATIONAL ISO
STANDARD 20988
First edition
2007-06-15
Air quality — Guidelines for estimating
measurement uncertainty
Qualité de l'air — Lignes directrices pour estimer l'incertitude de mesure
Reference number
ISO 20988:2007(E)
©
ISO 2007
ISO 20988:2007(E)
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ii © ISO 2007 – All rights reserved
ISO 20988:2007(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Symbols and abbreviated 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 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
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 Reporting . 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
ISO 20988:2007(E)
Foreword
ISO (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 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 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 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.
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 Committee ISO/TC 146, Air quality, Subcommittee SC 4, General
aspects.
iv © ISO 2007 – All rights reserved
ISO 20988:2007(E)
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
observations. 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
observations 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 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, 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 purpose of uncertainty estimation.
Uncertainties of results of measurement caused by incomplete time-coverage of measurement data are not
[2]
considered in this document, but in ISO 11222 . Uncertainties of results of measurement induced by
incomplete spatial coverage by measurement data are not considered in this document.
...
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