ISO 9241-221:2023

INTERNATIONAL ISO
STANDARD 9241-221
First edition
2023-08
Ergonomics of human-system
interaction —
Part 221:
Human-centred design process
assessment model
Ergonomie de l'interaction homme/système —
Partie 221: Modèle d'évaluation de processus de conception centrée
sur l'opérateur
Reference number
ISO 9241-221:2023(E)
© ISO 2023

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ISO 9241-221:2023(E)
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ISO 9241-221:2023(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 2
3.1 Terms and definitions . 2
3.2 Abbreviated terms . 2
4 Conformity . . 2
5 PAM and capability determination . 3
5.1 General . 3
5.2 Process capability levels and process attributes . 3
5.3 Process performance indicators . 4
5.4 Process capability indicators. 5
5.5 Process attribute rating . 5
5.6 Process capability level model . 6
6 Process reference model (PRM) and process performance indicators (PPIs) (Level
1) . 8
6.1 General . 8
6.2 HCP.1 process group: ensure enterprise focus on human-centred quality . 10
6.2.1 Purpose and outcomes of HCP.1 . . 10
6.2.2 HCP.1.1 – Incorporate human-centred quality in business strategy . 11
6.2.3 HCP.1.2 – Institutionalize human-centred quality .12
6.3 HCP.2 process group: enable human-centred design across projects and systems.13
6.3.1 Purpose and outcomes of HCP.2 . 13
6.3.2 HCP.2.1 – Integration of human-centred design . 14
6.3.3 HCP.2.2 – Resources for human-centred design . 16
6.3.4 HCP.2.3 – Authorization and control of human-centred quality . 17
6.4 HCP.3 process group: execute human-centred design within a project . 19
6.4.1 Purpose and outcomes of HCP.3 . 19
6.4.2 HCP.3.1 process sub-group: plan and manage human-centred design for
the project . 19
6.4.3 HCP.3.2 process sub-group: identify the context of use . 27
6.4.4 HCP.3.3 process sub-group: establish the user requirements .30
6.4.5 HCP.3.4 process sub-group: design solutions that meet user requirements .36
6.4.6 HCP.3.5 process sub-group: user-centred evaluation .40
6.5 HCP.4 process group: introduction, operation and end of life of a system . 45
6.5.1 Purpose and outcomes of HCP.4. 45
6.5.2 HCP.4.1 – Introducing the system .46
6.5.3 HCP.4.2 – Human-centred quality in operation .48
6.5.4 HCP.4.3 – Human-centred quality during upgrades .50
6.5.5 HCP.4.4 – Human-centred quality at the end of life of a system . 52
7 Process capability levels and process attributes (Levels 0 to 5) .53
7.1 General .53
7.2 Process capability level 0: Incomplete process .54
7.3 Process capability level 1: Performed process .54
7.3.1 General .54
7.3.2 PA 1.1 – Process performance process attribute .54
7.4 Process capability level 2: Managed process .54
7.4.1 General .54
7.4.2 PA 2.1 – Performance management process attribute .54
7.4.3 PA 2.2 – Documented information management process attribute .56
7.5 Process capability level 3: Established process .58
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ISO 9241-221:2023(E)
7.5.1 General .58
7.5.2 PA 3.1 – Process definition process attribute .58
7.5.3 PA 3.2 – Process deployment process attribute . 59
7.5.4 PA 3.3 – Process assurance process attribute .60
7.6 Process capability level 4: Predictable process . 61
7.6.1 General . 61
7.6.2 PA 4.1 – Quantitative analysis process attribute . 62
7.6.3 PA 4.2 – Quantitative control process attribute .63
7.7 Process capability level 5: Innovating process .64
7.7.1 General .64
7.7.2 PA 5.1 – Process innovation process attribute .64
Annex A (informative) Explanation of the process reference and PAMs .67
Annex B (informative) Conformity of the process assessment and reference models with
ISO/IEC 33004 .70
Annex C (informative) Attributes to look for in work products as part of an assessment .72
Bibliography . 101
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ISO 9241-221:2023(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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
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expressions related to conformity assessment, as well as information about ISO's adherence to
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 4,
Ergonomics of human-system interaction.
A list of all parts in the ISO 9241 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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ISO 9241-221:2023(E)
Introduction
This document focuses on the capability of human-centred design (HCD) processes and the maturity of
organizations in implementing HCD.
The primary intended users of this document are internal and external assessors or well-trained UX
professionals (such as HCD process managers or HCD quality managers) responsible for assessing HCD
processes in organizations that need to specify, assess and improve their HCD processes, according
to the process reference model (PRM) described in ISO 9241-220. The professionals responsible for
institutionalizing HCD in organizations, the primary intended users of ISO 9241-220, are also important
users of this document since this document intends to assess their work.
This document incorporates the processes from ISO 9241-220, as well as the process assessment model
(PAM) according to the process measurement framework for the assessment of process capability in
ISO/IEC 33020. The full titles of these standards are listed in the Bibliography.
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INTERNATIONAL STANDARD ISO 9241-221:2023(E)
Ergonomics of human-system interaction —
Part 221:
Human-centred design process assessment model
1 Scope
This document specifies the process references model (PRM) for human-centred design (HCD) according
to ISO 9241-220, as well as the process assessment model (PAM) for assessing these processes, based on
ISO/IEC 33020 and in accordance with the requirements of ISO/IEC 33004.
This HCD PAM contains a set of indicators to be considered while interpreting the intent of the HCD
PRM defined in ISO 9241-220. These indicators can also be applied when implementing a process
improvement programme post an assessment.
NOTE 1 The PRM in this document focuses on assessing HCD processes rather than system life cycle, for
example as in ISO/IEC/IEEE 15288, or software life cycle, as in ISO/IEC/IEEE 12207.
NOTE 2 If processes beyond the scope of ISO 9241-220 are required, appropriate processes from other PRMs,
such as ISO/IEC/IEEE 12207, ISO/IEC/IEEE 15288 or ISO/TS 18152, can be added based on the business needs of
the organization.
The intended application of this document is computer-based interactive systems. While the processes
apply to interactive systems that deliver services, they do not cover the design of those services. The
relevant aspects of the processes can also be applied to simple or non-computer-based interactive
systems.
NOTE 3 HCD concentrates on the human-centred aspects of design and not on other aspects of design, such as
mechanical construction, programming or the basic design of services.
The process descriptions in this document provide the basis for a rigorous assessment of an
enterprise’s capability to carry out human-centred processes in conformity with the ISO/IEC 33004
and ISO/IEC 33020.
This document is intended for use by organizations that want to address and improve their treatment
of human-centred design of either their internal systems or the products and services they provide, and
the procurement of systems and parts of systems. The processes can be applied by small- and medium-
sized enterprises as well as by large organizations.
NOTE 4 The scope of application of the PAM is the same as that of the PRM, which is described in
ISO 9241-220:2019, Clause 1.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes 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 9241-220:2019, Ergonomics of human-system interaction — Part 220: Processes for enabling, executing
and assessing human-centred design within organizations
ISO/IEC/IEEE 24765, Systems and software engineering — Vocabulary
ISO/IEC/IEEE 29119-1, Software and systems engineering — Software testing — Part 1: General concepts
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ISO 9241-221:2023(E)
ISO/IEC/IEEE 29119-3, Software and systems engineering — Software testing — Part 3: Test
documentation
ISO/IEC 33001, Information technology — Process assessment — Concepts and terminology
ISO/IEC 33020:2019, Information technology — Process assessment — Process measurement framework
for assessment of process capability
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9241-220, ISO/IEC/IEEE 24765,
ISO/IEC/IEEE 29119-1, ISO/IEC/IEEE 29119-3 and ISO/IEC 33001 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/
3.1.1
work product
documented information
artefact produced by a process
EXAMPLE Project plan, requirements specification, design documentation, source code, test plan, test
meeting minutes, schedules, budgets and incident reports.
Note 1 to entry: Work products are evidence of the achievement of process outcomes and of the performance of
the relevant activities.
[SOURCE: 9241-220:2019, 3.49, modified — Additional preferred term, "documented information",
added.]
3.2 Abbreviated terms
BP base practice
GP generic practice
HCD human-centred design
HCP human-centred process
IEEE Institute of Electrical and Electronics Engineers
PA process attribute
PAM process assessment model
PCI process capability indicator
PPI process performance indicator
PRM process reference model
WP work product
WPC work product characteristic
4 Conformity
The HCD PAM and PRM conform with ISO/IEC 33004 and can be used as the basis for assessing process
capability.
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ISO 9241-221:2023(E)
ISO/IEC 33020 is used as an ISO/IEC 33003-conforming measurement framework. A statement of
conformity of the PAM and PRM with the requirements of ISO/IEC 33004 is provided in Annex B.
Tailoring shall conform with ISO 9241-220:2019, Clause 6 and Annex B.
5 PAM and capability determination
5.1 General
To determine the capability of human-centredness as part of the PAM, all processes defined by
ISO 9241-220 are chosen as the PRM and ISO/IEC 33020 is used as measurement framework.
The measurement framework provides the necessary requirements and rules for the capability
dimension (see also ISO/IEC 33020 and/or Annex A). It defines a schema which enables an assessor to
determine the capability level of a given process.
5.2 Process capability levels and process attributes
A process capability level is a set of process attributes (PAs) that work together to provide a major
enhancement in the capability to perform a process. PAs are features of a process that can be evaluated
on a scale of achievement, as a means to measure the capability of the process. PAs are applicable to all
processes. Each PA addresses a specific aspect of the capability level. The levels constitute a rational
way of progressing through improvement of the capability of any process. These capability levels are
defined as part of the measurement framework.
Process capability levels (Table 1) and PAs (Table 2) are identical to those defined in the process
measurement framework in ISO/IEC 33020:2019, 5.2.
Table 1 — Process capability levels according to ISO/IEC 33020
Level 0: The process is not implemented or fails to achieve its process purpose.
Incomplete process purpose
Level 1: The implemented process achieves its process purpose.
Performed process
Level 2: The performed process is implemented in a managed fashion (planned,
Managed process monitored and adjusted) and its documented information is appropri-
ately established, controlled and maintained.
Level 3: The managed process is implemented using a defined process which is
Established process assured and continually improved.
Level 4: The established process is performed predictively. Quantitative man-
Predictable process agement needs are identified and measurement data are collected and
analysed to identify assignable causes of variation. Corrective action is
taken to address assignable causes of variation.
Level 5:  The predictable process is continually improved to respond to changes
Innovating process through identified innovative approaches for process innovation.
Within the PAM of this document, the determination of capability is based upon the nine PAs defined in
ISO/IEC 33020:2019, Table 2.
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ISO 9241-221:2023(E)
Table 2 — Process attributes according to ISO/IEC 33020
Attribute ID Process attributes
Level 0: Incomplete process
Level 1: Performed process
PA 1.1 Process performance
Level 2: Managed process
PA 2.1 Performance management
PA 2.2 Documented information management
Level 3: Established process
PA 3.1 Process definition
PA 3.2 Process deployment
PA 3.3 Process assurance
Level 4: Predicted process
PA 4.1 Quantitative analysis
PA 4.2 Quantitative control
Level 5: Innovative process
PA 5.1 Process innovation
Assessment indicators are used to identify whether the process outcomes and the process attribute
outcomes (achievements) are given in processes of projects in organizational units.
In this document, there are two types of assessment indicators:
— Process performance indicators (PPIs), which apply exclusively to capability level 1. They provide
an indication of the extent of fulfilment of the process outcomes.
— Process capability indicators (PCIs), which apply to capability levels 1 to 5. They provide an
indication of the extent of fulfilment of the process attribute achievements.
NOTE Assessment indicators are used to confirm that certain practices were performed, as shown by
evidence collected during an assessment. All such evidence comes either from the examination of work products
of the processes assessed or from statements made by the performers and managers of the processes. The
existence of base practices and work products provide evidence of the performance of the processes associated
with them. Similarly, the existence of process capability indicators provides evidence of process capability.
The evidence obtained should be recorded in a form that clearly relates to the associated assessment
indicator to support the assessor’s judgement that can be confirmed or verified as required by
ISO/IEC 33002.
5.3 Process performance indicators
Types of PPI are:
— base practices (BPs);
— work products (WPs) [in combination with work product characteristics (WPCs)].
Both BPs and WPs relate to one or more process outcomes. Consequently, BPs and WPs are always
process-specific and not generic. BPs represent activity-oriented indicators. WPs represent result-
oriented indicators. Both BPs and WPs are used for judging the objective evidence that an assessor is to
collect and accumulate in the performance of an assessment.
NOTE The HCD PAM offers a set of WPCs (see Annex C) for each WP. These are meant to offer a good practice
and state-of-the-art knowledge guide for the assessor.
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ISO 9241-221:2023(E)
5.4 Process capability indicators
There is one type of PCI relevant for this document: generic practices (GPs).
GPs are activity-oriented indicators relating to one or more process attribute achievements. In contrast
to PPIs, they are of generic type, i.e. they apply to any process.
The corresponding process capability levels and PAs for levels 0 to 5 are detailed in Clause 7.
NOTE An assessor collects and accumulates evidence supporting PCI during an assessment. In that respect,
GPs are alternative indicator sets the assessor can use.
5.5 Process attribute rating
To enable the rating, the measurement framework provides PAs defining a measurable property of
process capability. Each PA is assigned to a specific capability level. The extent of achievement of a
certain PA is represented by means of a rating based on a defined rating scale. The rules from which an
assessor can derive a final capability level for a given process are represented by a process capability
level model. The HCD PAM uses the measurement framework defined in ISO/IEC 33020.
NOTE It can be seen as good practice that at least two assessors conduct a representative HCD process
assessment: a lead assessor leading the assessment and a co-assessor supporting. It is useful if at least one of the
assessors has experience in mapping the HCD processes of the HCD PRM to organizations.
To support the rating of PAs, the ISO/IEC 33020 measurement framework provides a defined rating
scale with an option for refinement, different rating methods and different aggregation methods
depending on the class of the assessment (e.g. required for organizational maturity assessments). For
the rating scale within the process measurement framework, a PA is a measurable property of process
capability. A PA rating is a judgement of the degree of achievement of the PA for the assessed process.
The rating scale is defined by ISO/IEC 33020, as shown in Table 3.
Table 3 — Rating scale according to ISO/IEC 33020
N Not achieved There is little or no evidence of achievement of the defined PA in the assessed
process.
P Partially achieved There is some evidence of an approach to, and some achievement of, the defined
PA in the assessed process. Some aspects of achievement of the PA can be un-
predictable.
L Largely achieved There is evidence of a systematic approach to, and significant achievement of, the
defined PA in the assessed process. Some weaknesses related to this PA can exist
in the assessed process.
F Fully achieved There is evidence of a complete and systematic approach to, and full achieve-
ment of, the defined PA in the assessed process. No significant weaknesses
related to this PA exist in the assessed process.
For the rating of the degree of achievement of each process attribute, the rating scale of ISO/IEC 33020
is used: not achieved, partially achieved, largely achieved, fully achieved. This ordinal scale shall be
understood in terms of percentage achievement of a process attribute (shown in Table 4).
Table 4 — Rating scale percentage values according to ISO/IEC 33020
N Not achieved 0 to ≤ 15 % achievement
P Partially achieved > 15 % to ≤ 50 % achievement
L Largely achieved > 50 % to ≤ 85 % achievement
F Fully achieved > 85 % to ≤ 100 % achievement
The ordinal scale may be further refined for the measures P and L as defined in ISO/IEC 33020:2019,
Table 5.
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ISO 9241-221:2023(E)
The rating shall follow the rating defined in Table 5.
Table 5 — Refinement of rating scale and rating criteria accordin
...