CEN/TR 10350:2009
(Main)Analysis of steels and irons - Internal laboratory procedure for checking the accuracy of an analytical method by using Certified Reference Materials
Analysis of steels and irons - Internal laboratory procedure for checking the accuracy of an analytical method by using Certified Reference Materials
The present statistical procedure describes how to check results for absence of bias by comparison of these analytical results with those obtained during the certification of CRMs.
If the resulting data confirm the absence of bias, the method may be considered accurate when applied to all steels and irons whose composition ranges are adequately covered or bounded by the CRMs used.
The resulting data give also an estimate of the repeatability and/or the intermediate precision ("intralaboratory reproducibility") for the CRMs used. The comparison of these analytical data with the repeatability data obtained during the certification may also be performed depending on the strict purpose of the method under consideration.
NOTE 1 For the purpose of this Technical Report, the use of existing CRMs is essential for the assessment of the trueness, but it may be only indicative for the other statistical data.
NOTE 2 This Technical Report does not describe the use of CRMs as calibrants, this subject being treated in ISO Guide 32.
Analyse von Stahl und Eisen - Laboratoriumsinternes Verfahren zur Überprüfung der Richtigkeit eines Analysenverfahrens mit Hilfe zertifizierter Referenzmaterialien
Analyse des aciers et des fontes - Méthode de contrôle intralaboratoire de l'exactitude d'une procédure analytique au moyen de Matériaux de Référence Certifiés
La présente procédure statistique décrit comment contrôler des résultats pour vérifier l’absence de biais par
comparaison de ces résultats d’analyse à ceux obtenus au cours de la certification de MRC.
Si les données obtenues confirment l'absence de biais, la méthode peut être considérée comme exacte
lorsqu'elle est appliquée à des aciers et à des fontes dont les compositions sont correctement couvertes ou
délimitées par celles des MRC utilisés.
Les données obtenues donnent également une estimation de la répétabilité et/ou de la fidélité
intermédiaire ("reproductibilité intralaboratoire") pour les MRC utilisés. La comparaison de ces données
aux données de répétabilité obtenues au cours de la certification peut également être effectuée en fonction de
l'objectif strict de la méthode à contrôler.
NOTE 1 Pour l'objectif du présent Rapport Technique, l'utilisation de MRC existants est essentielle pour attester la
justesse, mais elle ne peut être qu'indicative pour les autres données statistiques.
NOTE 2 Le présent Rapport Technique ne décrit pas l'utilisation des MRC comme étalons, ce sujet étant traité dans le
Guide ISO 32.
Analize jekla in železa - Mednarodni laboratorijski postopek za preverjanje ujemanja v analizni metodi z uporabo certificiranih referenčnih materialov
Pričujoči statistični postopek opisuje, kako preveriti rezultate glede nepristranskosti s primerjavo teh analitičnih rezultatov z tistimi, ki so bili pridobljeni med certificiranjem CRMs. Če dobljeni podatki potrdijo nepristranskost, se lahko metoda šteje za točno, kadar se uporabi za vsa jekla in železa, katerih razpon sestave je v zadostni meri zajet ali omejen z uporabljenimi CRMs. Dobljeni podatki prav tako podajo oceno ponovljivosti in/ali vmesne natančnosti (»intralaboratorijska ponovljivost«) za uporabljene CRMs. Primerjava teh analitičnih podatkov s ponovljivimi podatki, pridobljenimi med certificiranjem, se prav tako lahko izvede glede na strog namen metode, ki se obravnava. OPOMBA 1: Za namen tega tehničnega poročila je uporaba obstoječih CRMs bistvena za oceno pravilnosti, vendar lahko služijo ostalim statističnim podatkom zgolj okvirno. OPOMBA 2: To tehnično poročilo ne opisuje uporabe CRMs kot umeril, saj je to področje obravnavano v Priročniku ISO 32.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-februar-2010
$QDOL]HMHNODLQåHOH]D0HGQDURGQLODERUDWRULMVNLSRVWRSHN]DSUHYHUMDQMH
XMHPDQMDYDQDOL]QLPHWRGL]XSRUDERFHUWLILFLUDQLKUHIHUHQþQLKPDWHULDORY
Analysis of steels and irons - Internal laboratory procedure for checking the accuracy of
an analytical method by using Certified Reference Materials
Analyse von Stahl und Eisen - Laboratoriumsinternes Verfahren zur Überprüfung der
Richtigkeit eines Analysenverfahrens mit Hilfe zertifizierter Referenzmaterialien
Analyse des aciers et des fontes - Méthode de contrôle intralaboratoire de l'exactitude
d'une procédure analytique au moyen de Matériaux de Référence Certifiés
Ta slovenski standard je istoveten z: CEN/TR 10350:2009
ICS:
77.040.30 Kemijska analiza kovin Chemical analysis of metals
77.080.01 Železne kovine na splošno Ferrous metals in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL REPORT
CEN/TR 10350
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
December 2009
ICS 77.040.30
English Version
Analysis of steels and irons - Internal laboratory procedure for
checking the accuracy of an analytical method by using Certified
Reference Materials
Analyse des aciers et des fontes - Méthode de contrôle Analyse von Stahl und Eisen - Laboratoriumsinternes
intralaboratoire de l'exactitude d'une procédure analytique Verfahren zur Überprüfung der Richtigkeit eines
au moyen de Matériaux de Référence Certifiés Analysenverfahrens mit Hilfe zertifizierter
Referenzmaterialien
This Technical Report was approved by CEN on 26 October 2009. It has been drawn up by the Technical Committee ECISS/TC 20.
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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 10350:2009: E
worldwide for CEN national Members.
Contents Page
Foreword .3
Introduction .4
1 Scope .5
2 Principle .5
3 Definitions .5
4 Procedure .8
4.1 General .8
4.2 Number of replicate determinations .8
4.3 CRMs .9
4.4 Determinations .9
5 Evaluation of precision . 10
5.1 Procedure . 10
5.2 Evaluation . 11
6 Assessment of the trueness . 11
6.1 Procedure . 11
6.2 Assessment . 12
7 Conclusion . 12
Annex A (informative) Symbols used . 13
Annex B (informative) Table of the χχχχ distribution . 14
Annex C (informative) Examples . 15
Bibliography . 23
Foreword
This document (CEN/TR 10350:2009) has been prepared by Technical Committee ECISS/TC 20 “Methods of
chemical analysis of ferrous products”, the secretariat of which is held by SIS.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes IC 5:1986.
Introduction
The aim of this Technical Report is to define a procedure for checking, in each specific laboratory, the
accuracy of an analytical method by the application of statistical principles to the analytical results obtained on
Certified Reference Materials (CRMs).
This Technical Report is an adaptation of ISO Guide 33 mostly for the specific cases where EURONORM-
CRMs are used for checking, in an intralaboratory context, the accuracy of an analytical method.
Nevertheless, it may be adopted in any other case where CRMs selected have similar quality levels to those
of EURONORM-CRMs.
1 Scope
The present statistical procedure describes how to check results for absence of bias by comparison of these
analytical results with those obtained during the certification of CRMs.
If the resulting data confirm the absence of bias, the method may be considered accurate when applied to all
steels and irons whose composition ranges are adequately covered or bounded by the CRMs used.
The resulting data give also an estimate of the repeatability and/or the intermediate precision ("intralaboratory
reproducibility") for the CRMs used. The comparison of these analytical data with the repeatability data
obtained during the certification may also be performed depending on the strict purpose of the method under
consideration.
NOTE 1 For the purpose of this Technical Report, the use of existing CRMs is essential for the assessment of the
trueness, but it may be only indicative for the other statistical data.
NOTE 2 This Technical Report does not describe the use of CRMs as calibrants, this subject being treated in
ISO Guide 32.
2 Principle
This Technical Report describes a procedure for checking an analytical method used in a specific laboratory
by using data obtained from the analysis of CRMs.
The absence of bias ascertained with CRMs can be extended to the trueness of further analytical samples
adequately covered or bounded by the selected CRMs. Nevertheless it should be underlined that this
Technical Report is not appropriate for the assessment of the repeatability and/or the intermediate precision
data of the further analytical samples to be tested by the analytical method under consideration.
Checking the trueness of an analytical method as applied by a specific laboratory involves the comparison of
the mean value of the analytical results obtained by using CRMs with the certified value of each CRM selected.
The standard deviation of the intralaboratory means of the selected CRMs is taken into account when making
this comparison. Moreover, adjustment values chosen in advance by the laboratory, according to economic or
technical limitations or stipulations are also taken into account.
3 Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
certified reference material
CRM
reference material characterized by a metrologically valid procedure for one or more specified properties,
accompanied by a certificate that provides the value of the specified property, its associated uncertainty, and
a statement of metrological traceability
NOTE 1 The concept of value includes qualitative attributes such as identity or sequence. Uncertainties for such
attributes may be expressed as probabilities.
NOTE 2 Metrologically valid procedures for the production and certification of reference materials are given in, among
others, ISO Guides 34 and 35.
NOTE 3 ISO Guide 31 gives guidance on the contents of certificates.
NOTE 4 VIM has an analogous definition (ISO/IEC Guide 99:2007, 5.14).
[ISO Guide 30; Amendment 1:2008]
3.2
reference material
RM
material, sufficiently homogeneous and stable with respect to one or more specified properties, which has
been established to be fit for its intended use in a measurement process
NOTE 1 "RM" is a generic term.
NOTE 2 Properties can be quantitative or qualitative, e.g. identity of substances or species.
NOTE 3 Uses may include the calibration of a measurement system, assessment of a measurement procedure,
assigning values to other materials, and quality control.
NOTE 4 A single RM cannot be used for both calibration and validation of results in the same measurement procedure.
NOTE 5 VIM has an analogous definition (ISO/IEC Guide 99:2007, 5.13), but restricts the term “measurement” to apply
to quantitative values and not to qualitative properties. However, NOTE 3 of ISO/IEC Guide 99:2007, 5.13, specifically
includes the concept of qualitative attributes, called “nominal properties”.
[ISO Guide 30; Amendment 1:2008]
3.3
accuracy
closeness of agreement between a test result and the true value
NOTE 1 In practice, the accepted reference value is substituted for the true value.
NOTE 2 The term "accuracy", when applied to a set of test or measurement results, involves a combination of random
components and common systematic error or bias component.
NOTE 3 Accuracy refers to a combination of trueness and precision.
[ISO 3534-2:2006, 3.3.1]
3.4
bias
difference between the expectation of a test result or a measurement result and a true value
NOTE 1 Bias is the total systematic error as contrasted to random error. There may be one or more systematic error
components contributing to the bias. A larger systematic difference from the true value is reflected by a larger bias value.
NOTE 2 The bias of a measuring instrument is normally estimated by averaging the error of indication over an
appropriate number of repeated measurements. The error of indication is the "indication of a measuring instrument minus
a true value of the corresponding input quantity".
NOTE 3 In practice, the accepted reference value is substituted for the true value.
[ISO 3534-2:2006, 3.3.2]
3.5
precision
closeness of agreement between independent test/measurement results obtained under stipulated conditions
NOTE 1 Precision depends only on the distribution of random errors and does not relate to the true value or the
specified value.
NOTE 2 The measure of precision is usually expressed in terms of imprecision and computed as a standard deviation
of the test results or measurement results. Less precision is reflected by a larger standard deviation.
NOTE 3 Quantitative measures of precision depend critically on the stipulated conditions. Repeatability conditions and
reproducibility conditions are particular sets of extreme stipulated conditions.
[ISO 3534-2:2006, 3.3.4]
3.6
repeatability
precision under repeatability conditions
[ISO 3434-2:2006, 3.3.5]
3.7
repeatability conditions
conditions where independent test/measurement results are obtained with the same method on identical
test/measurement items in the same test or measuring facility by the same operator using the same
equipment within short intervals of time
NOTE Repeatability conditions include:
a) the same measurement procedure or test procedure;
b) the same operator;
c) the same measuring or test equipment used under the same conditions;
d) the same location;
e) repetition over a short period of time.
[ISO 3434-2:2006, 3.3.6]
3.8
reproducibility
precision under reproducibility conditions
NOTE 1 Reproducibility can be expressed quantitatively in terms of the dispersion characteristics of the results.
NOTE 2 Results are usually understood to be corrected results.
[ISO 3534-2:2006, 3.3.10]
NOTE 3 This definition is not used in the present document: it is given only to clarify the next item.
3.9
reproducibility conditions
observation conditions where independent test/measurement results are obtained with the same method on
identical test/measurement items in different test or measurement facilities with different operators using
different equipment
[ISO 3534-2:2006, 3.3.11]
3.10
intermediate precision
precision under intermediate precision conditions
[ISO 3534-2:2006, 3.3.15]
...
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