ISO/IEC 25021:2012
(Main)Systems and software engineering — Systems and software Quality Requirements and Evaluation (SQuaRE) — Quality measure elements
Systems and software engineering — Systems and software Quality Requirements and Evaluation (SQuaRE) — Quality measure elements
ISO/IEC 25021:2012 provides guides to specify Quality Measure Elements (QME) and initial set of QME as examples. QME is a measure defined in terms of a property and the measurement method for quantifying it, including optionally the transformation by a mathematical function. ISO/IEC 25021:2012 is intended to be used throughout the system and software product life cycle used with other documents of the ISO/IEC 250nn SQuaRE series, especially ISO/IEC 25022, ISO/IEC 25023 and ISO/IEC 25024.
Ingénierie des systèmes et du logiciel — Exigences de qualité et évaluation des systèmes et du logiciel (SQuaRE) — Éléments de mesure de la qualité
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INTERNATIONAL ISO/IEC
STANDARD 25021
First edition
2012-11-01
Systems and software engineering —
Systems and software Quality
Requirements and Evaluation
(SQuaRE) — Quality measure elements
Ingénierie des systèmes et du logiciel — Exigences de qualité et
évaluation des systèmes et du logiciel (SQuaRE) — Éléments de
mesure de la qualité
Reference number
©
ISO/IEC 2012
© ISO/IEC 2012
All rights reserved. Unless otherwise specified, no part 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
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO/IEC 2012 – All rights reserved
Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Conformance . 1
3 Normative references . 1
4 Terms and definitions . 2
5 Abbreviated terms . 4
6 Quality measure elements concept . 4
6.1 Presentation of the measurement method model . 4
6.2 Table format of QMEs . 7
Annex A (informative) Examples of QMEs . 12
Annex B (informative) Guide for Designing a Quality Measure Element (QME) . 27
Annex C (informative) Additional Examples of QME and proposed expansion . 30
Annex D (informative) Measurement scale type . 36
Bibliography . 37
© ISO/IEC 2012 – All rights reserved iii
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national 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 and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 25021 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 7, Software and System Engineering.
This first edition of International Standard ISO/IEC 25021 cancels and replaces the first edition of
Technical Report ISO/IEC TR 25021:2007.
The SQuaRE series of standards consists of the following divisions under the general title Systems and
Software Quality Requirements and Evaluation (SQuaRE):
ISO/IEC 2500n, Quality Management Division,
ISO/IEC 2501n, Quality Model Division,
ISO/IEC 2502n, Quality Measurement Division,
ISO/IEC 2503n, Quality Requirements Division, and
ISO/IEC 2504n, Quality Evaluation Division.
iv © ISO/IEC 2012 – All rights reserved
Introduction
The purpose of this International Standard is to define and/or design an initial set of Quality Measure
Elements (QME) to be used throughout the product life cycle for the purpose of Systems and Software Quality
Requirements and Evaluation (SQuaRE). The document also gives a set of rules to design a QME or verify
the design of an existing QME. The content of this document constitutes the link between the ISO/IEC 9126
series of standards and the subsequent SQuaRE series of standards.
A number of QMEs for quality measures that quantify some of the characteristic and subcharacteristic
represent an initial list, which is to be used during the construction of the quality measures as referenced in
ISO/IEC TR 9126-2, ISO/IEC TR 9126-3 and ISO/IEC TR 9126-4. Quality measures presented in the
SQuaRE series (Figures 1, 2) were extracted from ISO/IEC TR 9126 series but it is not the only source. When
evaluating selected quality measures, the user should first understand the definition of each property related
to a QME used within the selected quality measures.
The main purposes of defining and using the Quality Measures Elements (QMEs) in this document are:
To provide guidance for organisations developing and implementing their own QMEs;
To promote the consistent use of specific QME for measuring and using the product properties that are
relevant to different product quality characteristics and subcharacteristics;
To help identify a set of QMEs that are uniquely required to derive all the quality measures for a given set
of characteristics or a set of subcharacteristics of a product.
The QMEs are the common components of a number of quality measures. The intended usage of this
International standard is that users will be able to select and define relevant valid QMEs to define internal,
external, data or quality-in-use quality measures. Then, these can be used for quality requirements definition,
products evaluation and quality assessment but not necessary limited to those. It is therefore recommended to
use this document prior or together with the ISO/IEC 2502n series of standards.
Quality Model
Division
2501n
Quality Quality
Quality Management
Requirements Evaluation
Division
Division Division
2500n
2503n 2504n
Quality Measurement
Division
2502n
Extension Division 25050-25099
Figure 1 — Organisation of the SQuaRE series of international standards
© ISO/IEC 2012 – All rights reserved v
Figure 1 illustrates the organisation of the SQuaRE series representing families of standards, further called
Divisions.
Figure 2 — Structure of the Quality Measurement Division
ISO/IEC TR 9126-4
ISO/IEC 25021
Quality in use measures
Quality measure elements
ISO/IEC TR 9126-3
Internal measures
(QME)
ISO/IEC TR 9126-2
External measures
ISO/IEC 9126-1
Quality model
Quality characteristics
SQuaRE Quality measures
Quality subcharacteristics
Quality measure 1
Quality measure 2
Quality measure 3
Quality measures
----- - -- -
Quality measure n
ISO/IEC 2502n
Figure 3 — The relationship of ISO/IEC 25021 as a link between the 9126 series and the SQuaRE series
of standard
vi © ISO/IEC 2012 – All rights reserved
The ISO/IEC 9126 series is composed of four documents that list and describe the characteristics,
subcharacteristics and quality measures that are referred to as the quality model. The SQuaRE quality models
categorize product quality into characteristics which are further subdivided into subcharacteristics and quality
properties (ISO/IEC 25010). Each quality measure within ISO/IEC 9126 series is composed of at least two
QMEs. The properties (of a product) are linked to the QME (ISO/IEC 25020), using a measurement method.
The 2502n series designs and describes quality measures and associated QMEs for all the quality
(sub)characteristics in the quality model.
© ISO/IEC 2012 – All rights reserved vii
INTERNATIONAL STANDARD ISO/IEC 25021:2012(E)
Systems and software engineering — Systems and software
Quality Requirements and Evaluation (SQuaRE) — Quality
measure elements
1 Scope
This International Standard contains the following information:
Requirements for defining QMEs as part of the specification of the product quality requirements with
examples (see 6.2 Tables 1 and 2);
NOTE Product quality includes system quality, software product quality, data quality and eventually system service
quality.
An initial set of QMEs, as examples (see Annex A Table A.1);
A guideline for defining and quantifying the property of the product (target entity) for QMEs (see Annex B)
This document is intended for, but not limited to, developers, acquirers and independent evaluators of
products, particularly those responsible for defining product quality requirements and for product evaluation.
This International Standard is applicable when defining the QMEs to be used to implement quality measures
such as those specified in ISO/IEC 25022, ISO/IEC 25023 and ISO/IEC 25024.
2 Conformance
When users define quality measures for a product, each of the referred QME shall be described according to
the information items of format specified in Table 1 (see 6.2). The same should be applied for modifying an
existing QME.
3 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 25000:2005, Software engineering — Software product Quality Requirements and Evaluation
(SQuaRE) — Guide to SQuaRE
ISO/IEC 25010:2011, Systems and software engineering — Systems and software product Quality
Requirements and Evaluation (SQuaRE) — System and software quality models
ISO/IEC 25020:2007, Software engineering — Software product Quality Requirements and Evaluation
(SQuaRE) — Measurement reference model and guide
ISO/IEC 15939:2007, Systems and software engineering — Measurement process
ISO/IEC Guide 99:2007, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
© ISO/IEC 2012 – All rights reserved 1
4 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 25000, ISO/IEC 25010,
ISO/IEC 25020, ISO/IEC 15939, ISO/IEC Guide 99, and the following apply. The following definitions are
replicated here for the convenience of the user of this document.
4.1
data quality
degree to which the characteristics of data satisfy stated and implied needs when used under specified
conditions
[ISO/IEC 25012:2008]
4.2
external measure of software quality
measure of the degree to which a software product enables the behavior of a system to satisfy stated and
implied needs for the system including the software to be used under specified conditions
NOTE 1 The behavior can be verified and/or validated by executing the software product during testing and operation.
NOTE 2 Based on the ISO/IEC 25000:2005 definition of external software quality.
NOTE 3 This definition was adapted from ISO/IEC 25010:2011.
4.3
internal measure of software quality
measure of the degree to which a set of static properties of a software product satisfies stated and implied
needs for the software product to be used under specified conditions
NOTE 1 Static properties include those that relate to the software architecture, structure and its components.
NOTE 2 Static properties can be verified by review, inspection, simulation and/or automated tools.
NOTE 3 This definition was adapted from ISO/IEC 25010:2011.
EXAMPLE Depending of the context specifications faults, design faults and code faults could be used as internal
quality measures.
NOTE 4 Based on the ISO/IEC 25000:2005 definition of internal software quality.
4.4
measure (noun)
variable to which a value is assigned as the result of measurement
NOTE The term “measures” is used to refer collectively to base measures, measures, and indicators.
[ISO/IEC 15939:2007]
4.5
measure (verb)
make a measurement
[ISO/IEC 25000:2005]
4.6
measurement
set of operations having the object of determining a value of a measure
[ISO/IEC 15939:2007]
NOTE Measurement can be nominal, ordinal, interval and ratio scale type.
2 © ISO/IEC 2012 – All rights reserved
4.7
measurement function
algorithm or calculation performed to combine two or more quality measure elements
NOTE This definition is modified from ISO/IEC 15939:2007 definition of measurement method.
4.8
measurement method
logical organisation of operations, described generically, used in measurement
NOTE This definition is modified from ISO/IEC 15939:2007 definition of measurement method.
4.9
measurement procedure
logical organisation of operations, app
...
INTERNATIONAL ISO/IEC
STANDARD 25021
First edition
2012-11-01
Systems and software engineering —
Systems and software Quality
Requirements and Evaluation
(SQuaRE) — Quality measure elements
Ingénierie des systèmes et du logiciel — Exigences de qualité et
évaluation des systèmes et du logiciel (SQuaRE) — Éléments de
mesure de la qualité
Reference number
©
ISO/IEC 2012
© ISO/IEC 2012
All rights reserved. Unless otherwise specified, no part 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
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO/IEC 2012 – All rights reserved
Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Conformance . 1
3 Normative references . 1
4 Terms and definitions . 2
5 Abbreviated terms . 4
6 Quality measure elements concept . 4
6.1 Presentation of the measurement method model . 4
6.2 Table format of QMEs . 7
Annex A (informative) Examples of QMEs . 12
Annex B (informative) Guide for Designing a Quality Measure Element (QME) . 27
Annex C (informative) Additional Examples of QME and proposed expansion . 30
Annex D (informative) Measurement scale type . 36
Bibliography . 37
© ISO/IEC 2012 – All rights reserved iii
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national 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 and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 25021 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 7, Software and System Engineering.
This first edition of International Standard ISO/IEC 25021 cancels and replaces the first edition of
Technical Report ISO/IEC TR 25021:2007.
The SQuaRE series of standards consists of the following divisions under the general title Systems and
Software Quality Requirements and Evaluation (SQuaRE):
ISO/IEC 2500n, Quality Management Division,
ISO/IEC 2501n, Quality Model Division,
ISO/IEC 2502n, Quality Measurement Division,
ISO/IEC 2503n, Quality Requirements Division, and
ISO/IEC 2504n, Quality Evaluation Division.
iv © ISO/IEC 2012 – All rights reserved
Introduction
The purpose of this International Standard is to define and/or design an initial set of Quality Measure
Elements (QME) to be used throughout the product life cycle for the purpose of Systems and Software Quality
Requirements and Evaluation (SQuaRE). The document also gives a set of rules to design a QME or verify
the design of an existing QME. The content of this document constitutes the link between the ISO/IEC 9126
series of standards and the subsequent SQuaRE series of standards.
A number of QMEs for quality measures that quantify some of the characteristic and subcharacteristic
represent an initial list, which is to be used during the construction of the quality measures as referenced in
ISO/IEC TR 9126-2, ISO/IEC TR 9126-3 and ISO/IEC TR 9126-4. Quality measures presented in the
SQuaRE series (Figures 1, 2) were extracted from ISO/IEC TR 9126 series but it is not the only source. When
evaluating selected quality measures, the user should first understand the definition of each property related
to a QME used within the selected quality measures.
The main purposes of defining and using the Quality Measures Elements (QMEs) in this document are:
To provide guidance for organisations developing and implementing their own QMEs;
To promote the consistent use of specific QME for measuring and using the product properties that are
relevant to different product quality characteristics and subcharacteristics;
To help identify a set of QMEs that are uniquely required to derive all the quality measures for a given set
of characteristics or a set of subcharacteristics of a product.
The QMEs are the common components of a number of quality measures. The intended usage of this
International standard is that users will be able to select and define relevant valid QMEs to define internal,
external, data or quality-in-use quality measures. Then, these can be used for quality requirements definition,
products evaluation and quality assessment but not necessary limited to those. It is therefore recommended to
use this document prior or together with the ISO/IEC 2502n series of standards.
Quality Model
Division
2501n
Quality Quality
Quality Management
Requirements Evaluation
Division
Division Division
2500n
2503n 2504n
Quality Measurement
Division
2502n
Extension Division 25050-25099
Figure 1 — Organisation of the SQuaRE series of international standards
© ISO/IEC 2012 – All rights reserved v
Figure 1 illustrates the organisation of the SQuaRE series representing families of standards, further called
Divisions.
Figure 2 — Structure of the Quality Measurement Division
ISO/IEC TR 9126-4
ISO/IEC 25021
Quality in use measures
Quality measure elements
ISO/IEC TR 9126-3
Internal measures
(QME)
ISO/IEC TR 9126-2
External measures
ISO/IEC 9126-1
Quality model
Quality characteristics
SQuaRE Quality measures
Quality subcharacteristics
Quality measure 1
Quality measure 2
Quality measure 3
Quality measures
----- - -- -
Quality measure n
ISO/IEC 2502n
Figure 3 — The relationship of ISO/IEC 25021 as a link between the 9126 series and the SQuaRE series
of standard
vi © ISO/IEC 2012 – All rights reserved
The ISO/IEC 9126 series is composed of four documents that list and describe the characteristics,
subcharacteristics and quality measures that are referred to as the quality model. The SQuaRE quality models
categorize product quality into characteristics which are further subdivided into subcharacteristics and quality
properties (ISO/IEC 25010). Each quality measure within ISO/IEC 9126 series is composed of at least two
QMEs. The properties (of a product) are linked to the QME (ISO/IEC 25020), using a measurement method.
The 2502n series designs and describes quality measures and associated QMEs for all the quality
(sub)characteristics in the quality model.
© ISO/IEC 2012 – All rights reserved vii
INTERNATIONAL STANDARD ISO/IEC 25021:2012(E)
Systems and software engineering — Systems and software
Quality Requirements and Evaluation (SQuaRE) — Quality
measure elements
1 Scope
This International Standard contains the following information:
Requirements for defining QMEs as part of the specification of the product quality requirements with
examples (see 6.2 Tables 1 and 2);
NOTE Product quality includes system quality, software product quality, data quality and eventually system service
quality.
An initial set of QMEs, as examples (see Annex A Table A.1);
A guideline for defining and quantifying the property of the product (target entity) for QMEs (see Annex B)
This document is intended for, but not limited to, developers, acquirers and independent evaluators of
products, particularly those responsible for defining product quality requirements and for product evaluation.
This International Standard is applicable when defining the QMEs to be used to implement quality measures
such as those specified in ISO/IEC 25022, ISO/IEC 25023 and ISO/IEC 25024.
2 Conformance
When users define quality measures for a product, each of the referred QME shall be described according to
the information items of format specified in Table 1 (see 6.2). The same should be applied for modifying an
existing QME.
3 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 25000:2005, Software engineering — Software product Quality Requirements and Evaluation
(SQuaRE) — Guide to SQuaRE
ISO/IEC 25010:2011, Systems and software engineering — Systems and software product Quality
Requirements and Evaluation (SQuaRE) — System and software quality models
ISO/IEC 25020:2007, Software engineering — Software product Quality Requirements and Evaluation
(SQuaRE) — Measurement reference model and guide
ISO/IEC 15939:2007, Systems and software engineering — Measurement process
ISO/IEC Guide 99:2007, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
© ISO/IEC 2012 – All rights reserved 1
4 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 25000, ISO/IEC 25010,
ISO/IEC 25020, ISO/IEC 15939, ISO/IEC Guide 99, and the following apply. The following definitions are
replicated here for the convenience of the user of this document.
4.1
data quality
degree to which the characteristics of data satisfy stated and implied needs when used under specified
conditions
[ISO/IEC 25012:2008]
4.2
external measure of software quality
measure of the degree to which a software product enables the behavior of a system to satisfy stated and
implied needs for the system including the software to be used under specified conditions
NOTE 1 The behavior can be verified and/or validated by executing the software product during testing and operation.
NOTE 2 Based on the ISO/IEC 25000:2005 definition of external software quality.
NOTE 3 This definition was adapted from ISO/IEC 25010:2011.
4.3
internal measure of software quality
measure of the degree to which a set of static properties of a software product satisfies stated and implied
needs for the software product to be used under specified conditions
NOTE 1 Static properties include those that relate to the software architecture, structure and its components.
NOTE 2 Static properties can be verified by review, inspection, simulation and/or automated tools.
NOTE 3 This definition was adapted from ISO/IEC 25010:2011.
EXAMPLE Depending of the context specifications faults, design faults and code faults could be used as internal
quality measures.
NOTE 4 Based on the ISO/IEC 25000:2005 definition of internal software quality.
4.4
measure (noun)
variable to which a value is assigned as the result of measurement
NOTE The term “measures” is used to refer collectively to base measures, measures, and indicators.
[ISO/IEC 15939:2007]
4.5
measure (verb)
make a measurement
[ISO/IEC 25000:2005]
4.6
measurement
set of operations having the object of determining a value of a measure
[ISO/IEC 15939:2007]
NOTE Measurement can be nominal, ordinal, interval and ratio scale type.
2 © ISO/IEC 2012 – All rights reserved
4.7
measurement function
algorithm or calculation performed to combine two or more quality measure elements
NOTE This definition is modified from ISO/IEC 15939:2007 definition of measurement method.
4.8
measurement method
logical organisation of operations, described generically, used in measurement
NOTE This definition is modified from ISO/IEC 15939:2007 definition of measurement method.
4.9
measurement procedure
logical organisation of operations, app
...
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