SIST EN ISO 4259-4:2022
(Main)Petroleum and related products - Precision of measurement methods and results - Part 4: Use of statistical control charts to validate 'in-statistical-control' status for the execution of a standard test method in a single laboratory (ISO 4259-4:2021)
Petroleum and related products - Precision of measurement methods and results - Part 4: Use of statistical control charts to validate 'in-statistical-control' status for the execution of a standard test method in a single laboratory (ISO 4259-4:2021)
This document specifies the methodology to determine if a laboratory is in control in the execution of a standard test method. By using statistical control charts and following this document the 'in-statistical-control' status is established and validated. In-statistical-control means the test results produced by the lab on control samples are reasonably consistent with expectation over time; with random variation scattered around a stable expected centre due to common causes only
This document explicitly defines ‘site precision’ conditions as single apparatus, multi-operators, over a long time horizon. It specifies control charts that are most appropriate for ISO TC28 test methods where the dominant common cause variation is associated with the long term, multiple operator conditions as described by "site precision" conditions. The control charts specified for determination of in-statistical-control are: Individual (I), Moving Range of 2 (MR2), Exponentially Weighted Moving Average (EWMA), and zone-based run rules (commonly known as Western Electric (WE)run rules.
The procedures in this document have been designed specifically for petroleum and petroleum related products, which are normally considered as homogeneous and for test methods which show normality in obtaining their results. However, the procedures described in this document can also be applied to other types of homogeneous products and test methods.
Mineralölerzeugnisse - Präzision von Messverfahren und Ergebnissen - Teil 4: Verwendung von Kontrollkarten zur Validierung des Status der statistischen Kontrolle bei der Durchführung von genormten Prüfverfahren in einem einzelnen Labor (ISO 4259-4:2021)
Dieses Dokument legt den Prozess und die Methodik für den Aufbau, den Betrieb und die Pflege von statistischen Kontrollkarten fest, um zu beurteilen, ob die Durchführung eines genormten Prüfverfahrens durch ein bestimmtes Laboratorium unter statistischer Prozesskontrolle erfolgt und wie der Zustand „unter statistischer Prozesskontrolle“ festgestellt und validiert wird.
Es legt Kontrollkarten fest, die sich am besten für die vom ISO/TC 28 festgelegten Prüfverfahren eignen, bei denen die vorherrschende Schwankung infolge gemeinsamer Ursachen mit den Bedingungen der Ausführung durch mehrere Bearbeiter über lange Zeiträume verbunden ist. Die für die Feststellung des Zustands „unter statistischer Prozesskontrolle“ festgelegten Kontrollkarten sind: „Einzelwert“ (I, en: individual), „gleitende Spannweite von 2“ (MR2, en: moving range of 2) und entweder der „exponentiell gewichtete gleitende Mittelwert“ (EWMA, en: exponentially weighted moving average) oder „zonenbasierte Laufregeln“ [en: zone-based run rules; ähnlich den Laufregeln von Western Electric (WE) [3]] als Empfindlichkeitsverbesserungsstrategie zur Unterstützung der I Karte.
Die in diesem Dokument angegebenen Verfahrensweisen wurden in erster Linie für numerische Ergebnisse entwickelt, die durch Prüfung von Kontrollproben erhalten wurden, die aus einer homogenen Quelle von Mineralölerzeugnissen und verwandten Produkten bezogen und in einer Weise aufbereitet wurden, die die Homogenität der interessierenden Eigenschaften beim Vergleich von Kontrollproben miteinander bewahrt. Wenn das Prüfverfahren es zulässt, wird ein zertifiziertes Referenzmaterial (CRM) als Kontrollprobe verwendet, vorausgesetzt, die Zusammensetzung der Probe ist repräsentativ für das zu prüfende Material und es handelt sich nicht um eine reine Verbindung; in diesem Fall legt das Laboratorium am besten seinen eigenen Mittelwert für die CRM-Probe fest.
Dieses Dokument ist anzuwenden für interessierende Eigenschaften, die (bekanntermaßen) über die Zeit stabil sind, und für Datensätze mit einer Auflösung, die ausreicht, um die Validierung der Annahme zu stützen, dass sich die Datenverteilung näherungsweise durch das Modell der (Gaußschen) Normalverteilung darstellen lässt. Für Situationen, in denen sich die Annahme nicht validieren lässt, werden Problemlösungsstrategien empfohlen.
Produits pétroliers et connexes - Fidélité des méthodes de mesure et de leurs résultats - Partie 4: Utilisation de cartes de contrôle statistique pour valider l’état 'sous maîtrise statistique' pour l’exécution d'une méthode d'essai normalisée dans un seul laboratoire (ISO 4259-4:2021)
Le présent document spécifie le processus et la méthodologie pour la construction, l'exploitation et la maintenance de cartes de contrôle statistique afin d'évaluer si l'exécution par un laboratoire d'une méthode d'essai normalisée est sous maîtrise statistique et comment établir et valider cet état «sous maîtrise statistique».
Il spécifie les cartes de contrôle les plus appropriées pour les méthodes d'essai de l’ISO/TC 28 dans lesquelles les principales variations de cause courante sont associées aux conditions de long terme et d'opérateurs multiples. Les cartes de contrôle spécifiées pour la détermination de la maîtrise statistique sont les suivantes: carte individuelle (I), carte à étendue mobile de 2 (MR2), et soit la moyenne mobile pondérée exponentiellement (EWMA) soit les règles de zone (similaires aux règles de Western Electric (WE)[3]) comme stratégie d'amélioration de la sensibilité en soutien de la carte I.
Les procédures décrites dans le présent document ont été principalement conçues pour les résultats numériques obtenus à partir d'essais d'échantillons de contrôle préparés à partir d'une source homogène de produits pétroliers et connexes de manière à préserver l'homogénéité des propriétés d'intérêt entre les échantillons de contrôle. Si la méthode de test le permet, un échantillon de matériau de référence certifié (CRM) est utilisé comme échantillon de contrôle à condition que la composition de l'échantillon soit représentative du matériau testé et qu'il ne s'agisse pas d'un composé pur; si cela est fait, alors le laboratoire établit au mieux sa propre moyenne pour l'échantillon CRM.
Le présent document s'applique aux propriétés d'intérêt connues pour leur stabilité au fil du temps, et pour des ensembles de données dont la résolution est suffisante pour permettre la validation de l'hypothèse selon laquelle la distribution des données peut être approchée par le modèle normal (de Gauss). Des stratégies d'atténuation sont suggérées pour les situations où l'hypothèse ne peut pas être validée.
Nafta in sorodni proizvodi - Natančnost merilnih metod in rezultatov - 4. del: Uporaba grafikonov statističnega nadzora stanja "pod statističnim nadzorom“ za izvajanje standardne preskusne metode v enem laboratoriju (ISO 4259-4:2021)
Ta dokument določa metodologijo za določitev, ali ima laboratorij pod nadzorom izvajanje standardne preskusne metode. Z uporabo grafikonov statističnega nadzora stanja in upoštevanjem tega dokumenta se vzpostavi in potrdi status »pod statističnim nadzorom«. »Pod statističnim nadzorom« pomeni, da so rezultati preskušanja, ki jih laboratorij pridobi pri kontrolnih vzorcih, razumno skladni s pričakovanji skozi čas, pri čemer so naključne variacije, razpršene okoli stabilnega pričakovanega središča, zgolj posledica splošnih vzrokov.
Dokument izrecno določa pogoje »natančnosti na mestu uporabe« kot eno napravo, ki jo uporablja več operaterjev v daljšem časovnem obdobju. Določa grafikone statističnega nadzora, ki so najprimernejši za preskusne metode ISO TC28, kjer je prevladujoča variacija s splošnim vzrokom povezana z dolgoročnimi pogoji z več operaterji, kot je opisano v pogojih o »natančnosti na mestu uporabe«. Grafikoni statističnega nadzora, namenjeni za določanje statusa »pod statističnim nadzorom«, so: individualno (I), pomično območje 2 (MR2), eksponentno ponderirano pomično povprečje (EWMA) in pravila izvajanja na podlagi območja (splošno znana kot pravila izvajanja Western Electric (WE)).
Postopki v tem dokumentu so bili zasnovani posebej za nafto in sorodne proizvode, ki so običajno homogeni, in za preskusne metode, ki pri pridobivanju rezultatov izkazujejo normalnost. Kljub temu se postopki, opisani v tem dokumentu, lahko uporabljajo tudi pri drugih vrstah homogenih proizvodov in preskusnih metod.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 4259-4:2022
01-september-2022
Nafta in sorodni proizvodi - Natančnost merilnih metod in rezultatov - 4. del:
Uporaba grafikonov statističnega nadzora stanja "pod statističnim nadzorom“ za
izvajanje standardne preskusne metode v enem laboratoriju (ISO 4259-4:2021)
Petroleum and related products - Precision of measurement methods and results - Part
4: Use of statistical control charts to validate 'in-statistical-control' status for the execution
of a standard test method in a single laboratory (ISO 4259-4:2021)
Mineralölerzeugnisse - Präzision von Messverfahren und Ergebnissen - Teil 4:
Verwendung von Kontrollkarten zur Validierung des Status der statistischen Kontrolle bei
der Durchführung von genormten Prüfverfahren in einem einzelnen Labor (ISO 4259-
4:2021)
Produits pétroliers et connexes - Fidélité des méthodes de mesure et de leurs résultats -
Partie 4: Utilisation de cartes de contrôle statistique pour valider l’état 'sous maîtrise
statistique' pour l’exécution d'une méthode d'essai normalisée dans un seul laboratoire
(ISO 4259-4:2021)
Ta slovenski standard je istoveten z: EN ISO 4259-4:2022
ICS:
75.080 Naftni proizvodi na splošno Petroleum products in
general
75.180.30 Oprema za merjenje Volumetric equipment and
prostornine in merjenje measurements
SIST EN ISO 4259-4:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 4259-4:2022
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SIST EN ISO 4259-4:2022
EN ISO 4259-4
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2022
EUROPÄISCHE NORM
ICS 75.080
English Version
Petroleum and related products - Precision of
measurement methods and results - Part 4: Use of
statistical control charts to validate 'in-statistical-control'
status for the execution of a standard test method in a
single laboratory (ISO 4259-4:2021)
Produits pétroliers et connexes - Fidélité des méthodes Mineralölerzeugnisse - Präzision von Messverfahren
de mesure et de leurs résultats - Partie 4: Utilisation de und Ergebnissen - Teil 4: Verwendung von
cartes de contrôle statistique pour valider l'état 'sous Kontrollkarten zur Validierung des Status der
maîtrise statistique' pour l'exécution d'une méthode statistischen Kontrolle bei der Durchführung von
d'essai normalisée dans un seul laboratoire (ISO 4259- genormten Prüfverfahren in einem einzelnen Labor
4:2021) (ISO 4259-4:2021)
This European Standard was approved by CEN on 30 November 2021.
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-CENELEC 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-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4259-4:2022 E
worldwide for CEN national Members.
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SIST EN ISO 4259-4:2022
EN ISO 4259-4:2022 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 4259-4:2022
EN ISO 4259-4:2022 (E)
European foreword
This document (EN ISO 4259-4:2022) has been prepared by Technical Committee ISO/TC 28
"Petroleum and related products, fuels and lubricants from natural or synthetic sources" in
collaboration with Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related
products of petroleum, synthetic and biological origin” the secretariat of which is held by NEN.
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 2022, and conflicting national standards
shall be withdrawn at the latest by December 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 4259-4:2021 has been approved by CEN as EN ISO 4259-4:2022 without any
modification.
3
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SIST EN ISO 4259-4:2022
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SIST EN ISO 4259-4:2022
INTERNATIONAL ISO
STANDARD 4259-4
First edition
2021-12
Petroleum and related products —
Precision of measurement methods
and results —
Part 4:
Use of statistical control charts to
validate 'in-statistical-control' status
for the execution of a standard test
method in a single laboratory
Produits pétroliers et connexes — Fidélité des méthodes de mesure et
de leurs résultats —
Partie 4: Utilisation de cartes de contrôle statistique pour valider
l’état 'sous maîtrise statistique' pour l’exécution d'une méthode
d'essai normalisée dans un seul laboratoire
Reference number
ISO 4259-4:2021(E)
© ISO 2021
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SIST EN ISO 4259-4:2022
ISO 4259-4:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
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SIST EN ISO 4259-4:2022
ISO 4259-4:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Specific terms and definitions . 2
3.2 Symbols and abbreviated terms . 2
4 Statistical control in the execution of a standard test method by a laboratory.3
4.1 General . 3
4.2 Control chart description . 4
4.2.1 General . 4
4.2.2 I- and MR-charts . 4
4.2.3 I-chart sensitivity enhancement strategy . 4
4.2.4 In-statistical-control conditions . 5
4.3 Control chart work process . 5
4.3.1 General . 5
4.3.2 Stage 1 of control chart work process . 5
4.3.3 Stage 2 of control chart work process . 9
4.4 QC material batch change transition . 11
4.4.1 General . 11
4.4.2 Procedure 1, concurrent testing .12
4.4.3 Procedure 2, Q-chart .12
4.4.4 Procedure 3, dynamically updated I-chart with EWMA .12
5 Guidance for insufficient variation or non-normal data .13
5.1 General requirement . 13
5.2 How to deal with insufficient variation or non-normal data .13
5.2.1 Insufficient variation .13
5.2.2 Non-normal data . 14
Annex A (informative) Details of the control chart work process .15
Annex B (normative) Check procedures .34
Bibliography .36
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SIST EN ISO 4259-4:2022
ISO 4259-4:2021(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels
and lubricants from natural or synthetic sources, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 19, Gaseous and liquid fuels, lubricants and related
products of petroleum, synthetic and biological origin, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 4259 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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SIST EN ISO 4259-4:2022
ISO 4259-4:2021(E)
Introduction
In the current global business environment, measurement data ‘trustworthiness’ is a key business
driver and an implicit expectation from customers and regulatory entities. Data trustworthiness
means the data quality meets expectations and is ‘fit-for-use’. Trustworthy data can only be produced
by measurement systems that are demonstrated to be stable and are under common cause variation
only.
This document describes the applications of specific statistical control charts selected from those that
are widely used by the manufacturing sector for the purpose of monitoring and demonstrating the
in-statistical-control status of a laboratory in the execution of a standardized test method to produce
trustworthy data.
[9]
In ISO 4259-2 , the requirement for assessment of product quality conformance to specification, is to be
interpreted that each laboratory’s test result is obtained from a test method that is in-statistical-control
in terms of precision and bias, to be substantiated by in-house statistical quality control (SQC) charts
or other equivalent statistical techniques. While in-house techniques are used by many laboratories for
test method quality assurance, standardization on how to establish in-statistical-control is necessary
[9]
to ensure consistency in application of ISO 4259-2 . Addressing the aforementioned necessity is the
[1]
motivation of this document, which is based on ASTM D6299 .
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SIST EN ISO 4259-4:2022
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SIST EN ISO 4259-4:2022
INTERNATIONAL STANDARD ISO 4259-4:2021(E)
Petroleum and related products — Precision of
measurement methods and results —
Part 4:
Use of statistical control charts to validate 'in-statistical-
control' status for the execution of a standard test method
in a single laboratory
1 Scope
This document specifies the process and methodology for the construction, operation, and maintenance
of statistical control charts to assess if a laboratory's execution of a standard test method is in-
statistical-control and how to establish and validate the 'in-statistical-control' status.
It specifies control charts that are most appropriate for ISO/TC 28 test methods where the dominant
common cause variation is associated with the long term, multiple operator conditions. The control
charts specified for determination of in-statistical-control are: individual (I), moving range of 2 (MR ),
2
and either the exponentially weighted moving average (EWMA) or zone-based run rules [similar to
[3]
Western Electric (WE) run rules ] as sensitivity enhancement strategy to support the I-chart.
The procedures in this document have been primarily designed for numerical results obtained from
testing of control samples prepared from a homogenous source of petroleum and related products in a
manner that preserves the homogeneity of properties of interest between control samples. If the test
method permits, a certified reference material (CRM) sample is used as a control sample provided the
sample composition is representative of the material being tested and is not a pure compound; if this is
done then the laboratory best establishes its own mean for the CRM sample.
This document is applicable to properties of interest that are (known to be) stable over time, and for
data sets with sufficient resolution to support validation of the assumption that the data distribution
can be approximately represented by the normal (Gaussian) model. Mitigating strategies are suggested
for situations where the assumption cannot be validated.
2 Normative references
The following documents are referred to in the text in such a way that some of their content support
requirements of this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 4259-1:2017, Petroleum and related products — Precision of measurement methods and results —
Part 1: Determination of precision data in relation to methods of test
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the terms and definitions given in ISO 4259-1 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
1
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SIST EN ISO 4259-4:2022
ISO 4259-4:2021(E)
3.1 Specific terms and definitions
3.1.1
common cause
factors that contribute to common cause variation (3.1.2)
Note 1 to entry: See Figure 1 for illustration.
3.1.2
common cause variation
variation amongst results collected under site precision conditions (3.1.4) from repeated execution of
a test method on the same test material attributable to known, unknown, or unknowable factors that
are intentionally not or cannot be rigidly controlled as part of the normal and correct execution of all
aspects of the test method
3.1.3
in-statistical-control
situation wherein the test results produced by the user on control samples are reasonably consistent
with expectation over time with common cause variation scattered around a stable expected centre
3.1.4
site precision conditions
conditions under which single test results are obtained in time intervals, separated by at least 8 h, by
the testing population in a single laboratory executing the same test method using the same apparatus
on test specimens taken at random from the same material over the normal daily operating envelope
3.1.5
quality control sample
QC sample
specimen taken from a stable and homogeneous material with composition and properties similar
to sample normally tested by the laboratory, prepared in a manner that preserves the homogeneity
of property of interest between test specimens, stored in a manner that preserves the properties of
interest over time, and available in sufficient quantity for repeated long-term testing
3.2 Symbols and abbreviated terms
AD Anderson Darling
ARV assigned reference value
CRM certified reference material
EWMA exponentially weighted moving average
GESD generalized extreme studentized deviation
MR moving range of two
2
moving range average associated with s
MR known
known
PT proficiency testing
QC quality control
q-q quantile-quantile, term used to describe the plot type comparing the z-score of a data point with is
numerical value
a
s statistically pooled standard deviation obtained using final achieved standard deviations from a
known
group of retired control charts where all the final achieved control chart averages are determined
to be not statistically significantly different using the appropriate clause(s) in stage 1
a
The range spanned by the final achieved control chart averages are referred to as the working range associated with
s . See concept illustrated in Table 1.
known
2
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SIST EN ISO 4259-4:2022
ISO 4259-4:2021(E)
Table 1 — Statistically pooled standard deviation concept
Material Property (unit) s df Working range MR
known
known
summer gasoline vapour pressure (kpa) 0,55 60 49,85 to 50,68 0,62
winter gasoline vapour pressure (kpa) 0,83 85 104,67 to 105,91 0,93
4 Statistical control in the execution of a standard test method by a laboratory
4.1 General
The execution of a standard test method by a laboratory is in this document considered as the execution
of a series of inter-connected work processes. Each work process is subject to variation caused by
known, unknown, or sometimes unknowable causes that are inherent to a process over long time
horizon such that every outcome of the process is affected. These causes are referred to as common
causes. The effect on the final process outcome due to common causes are referred to as common cause
variation.
Common causes for variation can be grouped into 5 categories (environment, operator, equipment,
procedure and reagent material) using a technique known as a fishbone diagram. Due to common cause
variation, repeated execution of the same test method on the same material over a long-time horizon
yields results that are not numerically identical. This effect is illustrated in Figure 1.
Figure 1 — Fishbone diagram representation of common cause variation in the execution of a
test method
The complete process associated with the execution of the specific test method is said to be 'in-
statistical-control' if the process outcomes (test results) from repeated analysis of QC samples prepared
from the same material are reasonably consistent with expectation over time, with random variation
scattered around a stable centre due to common causes only.
To determine 'in-statistical-control', a multi-step and integrated work process involving use of
statistical control charts and a QC sample is required.
NOTE For simplicity, the word 'statistical' will be omitted and the term referred to as 'control charts'
throughout the rest of this document.
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SIST EN ISO 4259-4:2022
ISO 4259-4:2021(E)
4.2 Control chart description
4.2.1 General
Control charts appropriate for most petroleum industry test methods that yield numeric results are the
individual (I) chart, and the moving range of 2 (MR ) chart.
2
[2]
NOTE 1 The I-chart is also known as the X-chart, or the Shewhart chart .
NOTE 2 For simplicity, the MR chart is referred to as the moving range (MR) chart throughout the rest of this
2
document.
4.2.2 I- and MR-charts
The I-chart is a graphic display of individual QC sample test results (X) collected under site precision
conditions, plotted in chronological order, overlaid with a centre line, lower and upper decision limits
that require action if exceeded. These limits are herein referred to as I-chart lower and upper control
limits (LCL_X, UCL_X). The primary purpose of the I-chart is to monitor process centre stability over
time.
NOTE Since the primary interest is to monitor the stability and common cause variation of the test process
under site precision conditions over a long time horizon, replicate analysis obtained under repeatability
conditions (see ISO 4259-1) does not contribute towards this objective, as the variation due to common causes of
interest is not contained in replicate results collected under repeatability conditions.
The MR-chart is the successive difference (with no arithmetic sign) of two individual results in the
I-chart, plotted in chronological order, also overlaid with a centre line and an upper decision limit for
action, herein referred to as MR-chart upper control limit (UCL_MR). The primary purpose of the MR-
chart is to monitor common cause variation stability between successive QC sample results over time.
The decision limits for action for both charts as well as the conditions requiring action for the strategies
in 4.2.3 are based on a very low theoretical probability (<0,3 %) of “action required” decision for a
process that is in-statistical-control, using the Normal distribution (I-chart) and W distribution (MR-
chart) as the reference statistical models. Hence, these limits represent the expectation limits for the
process outcome if it is in-statistical-control.
4.2.3 I-chart sensitivity enhancement strategy
As a direct consequence of setting the action limits for the I-chart based on a low probability of
exceedance for a process that is in-statistical-control, these limits are not sensitive to detection of small
changes in the process centre. It is therefore necessary to support I-chart with additional sensitivity
enhancement strategies to overcome this shortcoming.
This document requires use of one of the following strategies in conjunction with the I-chart:
a) Strategy 1: Zone-based run rules. Action is required if any of the following run rule conditions is
present. For definitions of zones see 4.3.2:
— two out of three consecutive individual results in Zone A on one side of the centre line;
— four out of five consecutive individual results beyond Zone C on one side of the centre line;
— nine consecutive individual results on the same side of the centre line (above or below);
or,
b) Strategy 2: Exponentially weighted moving average (EWMA). Action is required if either one of the
following conditions occur:
— any exceedance of the EWMA action limits;
— nine consecutive individual results on the same side of the centre line (above or below).
4
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SIST EN ISO 4259-4:2022
ISO 4259-4:2021(E)
The EWMA is a ‘time-weighted moving average’ calculated using all data points up to the most current
one, the weighting of each datum reduced with age exponentially. The rate of this weight decay is
controlled by λ. It is re-calculated with the arrival of each new datum and is judged against its own
action limits (herein referred to as the EWMA-action limits). An EWMA with λ = 0,4 has similar
[4]
detection power as Strategy 1 .
Use of Strategy 2 is recommended due to the ease of implementation and lower expected false alarm
rate than Strategy 1.
4.2.4 In-statistical-control conditions
The complete process associated with the execution of a test method is deemed to be in-statistical-
control if all of the following conditions are met:
a) all individual contro
...
SLOVENSKI STANDARD
oSIST prEN ISO 4259-4:2021
01-marec-2021
Nafta in sorodni proizvodi - Natančnost merilnih metod in rezultatov - 4. del:
Uporaba grafikonov statističnega nadzora stanja "pod statističnim nadzorom“ za
izvajanje standardne preskusne metode v enem laboratoriju
Petroleum and related products -- Precision of measurement methods and results -- Part
4: Use of Statistical Control Charts to validate 'in-statistical-control' status for the
execution of a standard test method in a single laboratory
Mineralölerzeugnisse - Präzision von Messverfahren und Ergebnissen - Teil 4:
Verwendung von Kontrollkarten zur Validierung des Status der statistischen Kontrolle der
Durchführung von genormten Prüfverfahren in einem einzelnen Labor
Produits pétroliers -- Fidélité des méthodes de mesure et des résultats -- Partie 4:
Utiliser de Cartes Controls Statistique pour valider 'statu d'être en control statistique' par
exécution d'une méthode d'essai normalisé en une laboratoire uniquement
Ta slovenski standard je istoveten z: prEN ISO 4259-4
ICS:
75.080 Naftni proizvodi na splošno Petroleum products in
general
75.180.30 Oprema za merjenje Volumetric equipment and
prostornine in merjenje measurements
oSIST prEN ISO 4259-4:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 4259-4:2021
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oSIST prEN ISO 4259-4:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 4259-4
ISO/TC 28 Secretariat: NEN
Voting begins on: Voting terminates on:
2021-01-12 2021-04-06
Petroleum and related products — Precision of
measurement methods and results —
Part 4:
Use of Statistical Control Charts to validate 'in-statistical-
control' status for the execution of a standard test method
in a single laboratory
Produits pétroliers et connexes — Fidélité des méthodes de mesure et de leurs résultats —
Partie 4: Utilisation de Cartes de Contrôle Statistique pour valider l’état 'sous contrôle statistique' pour
l’exécution d'une méthode d'essai normalisée dans un seul laboratoire
ICS: 75.080
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 4259-4:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2021
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oSIST prEN ISO 4259-4:2021
ISO/DIS 4259-4:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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Email: copyright@iso.org
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Published in Switzerland
ii © ISO 2021 – All rights reserved
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oSIST prEN ISO 4259-4:2021
ISO/DIS 4259-4:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Specific terms and definitions . 2
3.2 Variables and abbreviations . 2
4 Statistical control in the execution of a standard test method by a laboratory .3
4.1 General . 3
4.2 Control Chart description . 4
4.2.1 General. 4
4.2.2 I- and MR-charts . 4
4.2.3 I-chart sensitivity enhancement strategy . 4
4.2.4 In statistical control conditions . 5
4.3 Control Chart Work Process . 5
4.3.1 General. 5
4.3.2 Stage 1 of Control Chart Work Process . 6
4.3.3 Stage 2 of Control Chart work process . 7
4.4 QC material batch change transition .10
4.4.1 General.10
4.4.2 Procedure 1, concurrent testing .10
4.4.3 Procedure 2, Q-chart.10
4.4.4 Procedure 3, dynamically updated I-chart with EWMA .10
5 Guidance for insufficient variation or non-normal data .11
5.1 General requirement .11
5.2 How to deal with insufficient variation or non-normal data .11
5.2.1 Insufficient variation .11
5.2.2 Non-normal data .12
Annex A (informative) Details of the Control Chart work process .13
Annex B (normative) Check procedures .30
Bibliography .32
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oSIST prEN ISO 4259-4:2021
ISO/DIS 4259-4:2021(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
U R L : w w w . is o . or g / is o/ f or ewor d . ht m l .
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels
and lubricants from natural or synthetic sources.
A list of all parts in the ISO 4259 series can be found on the ISO website.
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Introduction
In the current global business environment, measurement data ‘trustworthiness’ is a key business
driver and an implicit expectation from customers and Regulatory Entities. Data trustworthiness
means the data quality meets expectations, and is ‘fit-for-use’. Trustworthy data can only be produced
by measurement systems that are demonstrated to be stable and are under common cause variation
(3.2) only.
This document describes the applications of specific statistical control charts selected from the those
that are widely used by the manufacturing sector for the purpose of monitoring and demonstrating the
in-statistical-control status of a laboratory in the execution of a standardized test method to produce
trustworthy data.
In ISO 4259-2, the requirement for assessment of product quality conformance to specification, is to
be interpreted that each laboratory’s test result is obtained from a test method that is in statistical
control in terms of precision and bias, to be substantiated by in-house SQC charts or other equivalent
statistical techniques. While in-house techniques are used by many laboratories for test method
quality assurance, standardization on how to establish in-statistical-control is necessary to ensure
consistency in application of ISO 4259-2. Addressing the aforementioned necessity is the motivation of
[1]
this document, which is based on ASTM D6299 .
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oSIST prEN ISO 4259-4:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 4259-4:2021(E)
Petroleum and related products — Precision of
measurement methods and results —
Part 4:
Use of Statistical Control Charts to validate 'in-statistical-
control' status for the execution of a standard test method
in a single laboratory
1 Scope
This document specifies the work process and methodology for the construction, operation, and
maintenance of statistical control charts for the purpose of assessing if a laboratory's execution of
a standard test method is in statistical control. By using statistical control charts and following this
document the 'in-statistical-control' status is established and validated.
This document explicitly defines ‘site precision’ conditions as single apparatus, multi-operators, over
a long time horizon. It specifies control charts that are most appropriate for ISO/TC 28 test methods
where the dominant common cause variation is associated with the long term, multiple operator
conditions as described by “site precision” conditions. The control charts specified for determination
of in-statistical-control are: Individual (I), Moving Range of 2 (MR2), and either the Exponentially
Weighted Moving Average (EWMA) or zone-based run rules (similar to Western Electric (WE) run
rules) as sensitivity enhancement strategy to support the I-chart.
The procedures in this document have been primarily designed for numerical results obtained from
testing of control samples prepared from a homogenous source of petroleum and related products in a
manner that preserves the homogeneity of properties of interest between control samples.
This document applies to properties of interest that are (known to be) stable over time, and for data
sets with sufficient resolution to support validation of the assumption that the data distribution can
be approximately represented by the Normal (Gaussian) model. Mitigating strategies are suggested for
situations where the aforementioned assumption cannot be validated.
2 Normative references
The following documents are referred to in the text in such a way that some of their content support
requirements of this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 4259-1:2017, Petroleum and related products — Precision of measurement methods and results —
Part 1: Determination of precision data in relation to methods of test
ISO 4259-2, Petroleum and related products — Precision of measurement methods and results — Part 2:
Interpretation and application of precision data in relation to methods of test
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4259-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
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ISO/DIS 4259-4:2021(E)
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 Specific terms and definitions
3.1.1
common cause
factors that contribute to common cause variation.
Note 1 to entry: See Figure 1 for illustration.
3.1.2
common cause variation
variation amongst results collected under site precision conditions from repeated execution of a test
method on the same test material attributable to known, unknown, or unknowable factors that are
intentionally not or cannot be rigidly controlled as part of the normal and correct execution of all
aspects of the test method
3.1.3
special cause variation
variation of a magnitude that exceeds expectation from common cause variation
3.1.4
in-statistical-control
situation wherein the test results produced by the user on control samples are reasonably consistent
with expectation over time with common cause variation scattered around a stable expected centre
3.1.5
site precision conditions
conditions under which single test results are obtained in time intervals, separated by at least 8 h, by
the testing population in a single laboratory executing the same test method using the same apparatus
on test specimens taken at random from the same material over the normal daily operating envelope
3.1.6
control sample
QC sample
specimens taken from a stable and homogeneous material with composition and properties similar
to samples normally tested by the laboratory, prepared in a manner that preserves the homogeneity
of property of interest between test specimens, stored in a manner that preserves the properties of
interest over time, and available in sufficient quantity for repeated long term testing
3.2 Variables and abbreviations
3.2.1
AD
Anderson Darling
3.2.2
MR
known
moving range average associated with the s
known
3.2.3
q-q
quantile-quantile
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3.2.4
s
known
statistically pooled standard deviation obtained using final achieved standard deviations from a group
of retired control charts where all the final achieved control chart averages are within 1,5 s
known
Note 1 to entry: The range spanned by the final achieved control chart averages are referred to as the working
range associated with s . See concept illustrated in Table 1
known
Table 1 — Statistically pooled standard deviation concept
MR
material property (unit) S df working range
known
known
summer gasoline vapour pressure (kpa) 0,55 60 49,85 to 50,68 0,62
winter gasoline vapour pressure (kpa) 0,83 85 104,67 to 105,91 0,93
4 Statistical control in the execution of a standard test method by a laboratory
4.1 General
The execution of a standard test method by a laboratory is in this document considered as the execution
of a series of inter-connected work processes. Each work process is subject to variation caused by
known, unknown, or sometimes unknowable causes that are inherent in a process over long time
horizon such that every outcome of the process is affected. These causes are referred to as common
causes. The effect on the final process outcome due to common causes are referred to as common cause
variation.
Common causes for variation can be grouped into 5 categories (environment, operator, equipment,
procedure and reagent material) using a technique known as a Fishbone diagram. Due to common cause
variation, repeat execution of the same test method on the same material over a long time horizon will
yield results that are not numerically identical. This effect is illustrated in Figure 1.
Figure 1 — Fishbone diagram representation of common cause variation in the execution of a
test method
The complete process associated with the execution of the specific test method is said to be 'in statistical
control' if the process outcomes (test results) from repeated analysis of control (QC) samples prepared
from the same material are reasonably consistent with expectation over time; with random variation
scattered around a stable centre due to common causes only.
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oSIST prEN ISO 4259-4:2021
ISO/DIS 4259-4:2021(E)
To determine 'in statistical control', a multi-step and integrated work process involving use of statistical
control charts and a quality control (QC) material is required.
NOTE For simplicity, the term 'statistical' will be omitted and simply referred to as control charts for the
remainder of the document.
4.2 Control Chart description
4.2.1 General
Control Charts appropriate for most petroleum industry test methods that yield numeric results are
the Individual (I) chart, and the Moving Range of 2 (MR ) chart.
2
NOTE 1 The I-chart is also known as the X-chart, or, the Shewhart chart, named after its inventor, Dr Walter A.
Shewhart [2].
NOTE 2 For simplicity, the MR chart is referred to as the Moving Range (MR) chart throughout the rest of the
2
document.
4.2.2 I- and MR-charts
The I-chart is a graphic display of individual control sample test results (X) collected under site precision
conditions, plotted in chronological order, overlaid with a centre line, lower and upper decision limits that
require action if exceeded. These limits are herein referred to as I-chart lower and upper control limits
(LCL_X, UCL_X). The primary purpose of the I-chart is to monitor process centre stability over time.
NOTE Since the primary interest is to monitor the stability and common cause variation of the test process
under site precision conditions over a long time horizon, replicate analysis obtained under repeatability
conditions (see ISO 4259-1) does not contribute towards this objective, as the variation due to common causes of
interest is not contained in replicate results collected under repeatability conditions.
The MR-chart is the successive difference (with no arithmetic sign) of two individual results in the I-chart,
plotted in chronological order, also overlaid with a centre line and an upper decision limit for action,
herein referred to as MR-chart upper control limit (UCL_MR). The primary purpose of the MR-chart is to
monitor common cause variation stability between successive control sample results over time.
The decision limits for action for both charts as well as the conditions requiring action for the strategies
in 4.2.3 are based on a very low theoretical probability (<0,3 %) of “action required” decision for a
process that is in-statistical-control, using the Normal distribution (I-chart) and W distribution (MR-
chart) as the reference statistical models. Hence, these limits represent the expectation limits for the
process outcome if it is in-statistical-control.
4.2.3 I-chart sensitivity enhancement strategy
As a direct consequence of setting the action limits for the I-chart based on a low probability of
exceedance for a process that is in statistical control, these limits are not sensitive to detection of small
changes in the process centre. It is therefore necessary to support I-chart with additional sensitivity
enhancement strategies to overcome this shortcoming.
This document requires use of one of the following strategies in conjunction with the I-chart:
1) Strategy 1: Zone-based Run Rules. Action is required if any of the following Run Rule conditions
is present. For definitions of zones see 4.3.2 later in this document. These rules are similar to the
[3]
Western Electric (WE) Run Rules (named after the company that invented them ):
• two out of three consecutive individual results in Zone A on one side of the centre line
• four out of five consecutive individual results beyond Zone C on one side of the centre line
• nine consecutive individual results on one side of the centre line
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ISO/DIS 4259-4:2021(E)
or,
2) Strategy 2: the Exponentially Weighted Moving Average (EWMA). Action is required if either one of
the following conditions occur:
• one or more exceedance of the EWMA action limits
• nine consecutive individual results on the same side of the centre line (above or below).
The EWMA is a ‘time-weighted moving average’ calculated using all data points up to the most current
one, the weighting of each datum reduced with age exponentially. The rate of this weight decay is
controlled by λ. It is re-calculated with the arrival of each new datum, and is judged against its own
action limits (herein referred to as the EWMA-action limits). An EWMA with λ = 0.4 has similar
detection power as strategy 1.
NOTE Use of the EWMA with λ = 0,4 as an enhancement strategy was developed by Dr J. Stuart Hunter [4].
Use of Strategy 2 is recommended due to the ease of implementation and lower expected false alarm
rate than Strategy 1.
4.2.4 In statistical control conditions
The complete process associated with the execution of a test method execution is deemed to be in
statistical control if all of the following conditions are met:
1) all individual control sample results are within the I-chart action limits,
2) less than five (5) out of 12 (12) successive MR results exceed MR-chart action limit, and
3) no action required for the sensitivity enhancement chosen (strategy 1 or 2).
4.3 Control Chart Work Process
4.3.1 General
To determine if the complete process associated with the execution of a test method is 'in statistical
control', a two-stage multi-step work process involving use of control charts and QC material is specified
by this document.
Stage 1 comprises visual and statistical assessment of initial test results for a new batch of QC material
plotted in a chronological order (known as a run chart). This is followed by construction of the I-chart
and MR-chart using these results by overlaying the mean and the action limits onto the respective
charts. The action limits represent the boundaries within which the current and future test results and
MR for this QC material are expected to lie, on the assumption that the process is in statistical control
and the QC material remains unchanged. The control charts (I and MR)) constructed in Stage 1 are
deployed for Stage 2 if all in-statistical-control conditions (4.2.4) are met.
Stage 2 comprises of two modes, Operation and Maintenance. Under 'Operation', future test results
(for the QC material tested in Stage 1) as they arrive in chronological order are compared against
the established action limits and chosen enhancement strategy in Stage 1. Under 'Maintenance', the
statistics used in the computation of the control chart action limits from Stage 1 are re-assessed
periodically using newly accrued in-statistical-control results and updated as appropriate.
For this practice, the root-mean-square technique is used to compute the sample standard deviation
statistic, s.
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4.3.2 Stage 1 of Control Chart Work Process
The primary objective of Stage 1 is to establish initial means and action limits for the I, MR control
charts and implement the chosen enhancement strategy (4.3.2) for a specific batch of QC material using
chronologically obtained data and the Normal distribution as the reference model. The main steps are:
1) Prepare multiple control (QC) samples from a stable and homogeneous material with composition
and properties similar to samples normally tested by the laboratory.
2) Collect a minimum of 20 (20) QC sample test results under site precision conditions.
3) Plot the individual results chronologically (this is called a run chart) and study the plot for any
visually discernible transcription errors. Correct or discard obvious transcription errors.
4) Construct a quantile-quantile (q-q) plot (as shown in Annex A) and compute the Anderson-Darling
(A-D) statistic. Examine this plot in conjunction with the data for variation sufficiency. Proper
application of the control charts in this document require at least 6 unique values to provide
sufficient observable common cause variation. Insufficient variation in the data set will manifest
into the follow two outcomes:
a) q-q plot shows several distinct horizontal data clusters where each horizontal cluster represent
numerically identical data (see Clause 5)
b) A-D value exceeds the 0,01 sig. level of 1,0 by a large margin
If the total number of unique values is less than six (6), proceed directly to Clause 5 for guidance.
5) Perform a formal statistical assessment for outliers using GESD technique for outliers similar to
[5]
ISO 4259-1 (or check ASTM D7915 ). The recommended maximum number of outliers for 20 to 25
observations is 3 at 0,01 significance.
Reject identified outliers, obtain replacement results and repeat from step 4).
While not always possible, it is recommended that rejection of outliers be justified by corresponding
root cause(s).
6) Confirm the goodness-of-fit of the Normal distribution using the Anderson-Darling (A-D) statistic
computed from at least 20 non-outlier results.
− If A-D is less than 1,
...
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