ISO standards

Standards in usability and user-centred design

This document sets out the key international standards in the area of usability and user-centred design. The main body of standards in this area are those produced by ISO (the International Standards Organisation), to which individual national standards organisations have input. Most are also adopted as European (CEN) standards. Copies can be obtained from ISO or from national standards bodies.

In addition to standards, there are a large number of guidelines that have been published by individuals and organisations around the world. If designing a particular type of product (e.g. a piece of PC software) it can be worth consulting guidelines specific to that type of product (e.g. Interface design guidelines for Microsoft Windows, or the Apple Desktop). There are also guidelines that provide recommendations concerning accessibility of different types of products and systems for users with disabilities.

Usability and user-centred design standards can be divided up into 3 main categories:

• Product usage characteristics (how well users perform with it, how satisfied they are with it)
• Product interface attributes (design of the interface and interaction)
• Development process (activities carried out during product development)

Some standards (for example, those relating to software in ISO 9241) set out few mandatory requirements but instead set out guidelines and conditional requirements. When using such standards it is particularly important to have a good understanding of the product's context of use, user characteristics, user tasks, user requirements, and so on.

1. Standards dealing with product usage characteristics

ISO 9241-11 (1998) Guidance on Usability

A central standard in usability, explaining how to identify the information that it is necessary to take into account when specifying or evaluating usability in terms of measures of user performance and satisfaction. Guidance is given on how to describe the context of use of the product (hardware, software or service) and required measures of usability. It includes an explanation of how the usability of a product can be specified and evaluated as part of a quality system (e.g. one conforming to ISO 9001).

ISO 9241-11 defines usability as:

Other relevant standards:

• ISO/IEC 25010 (2011) Systems and software engineering - Systems and software Quality Requirements and Evaluation (SQuaRE) - System and software quality model

2. Standards dealing with product interface attributes

These standards deal with characteristics of the product itself and can be used to specify and evaluate details of the user interface of the product and how it works. However, it is important to note that they must be interpreted and applied based on the context of use of the particular product in question.

ISO/IEC 9126-1 (2001) Software Engineering - Product quality - Part 1: Quality model

This standard specifies a two-part model for software product quality:

• a) Internal quality divided into six characteristics: functionality, reliability, efficiency, usability, maintainability and portability. External quality is manifested when the software is used as a part of a computer system, and is the result of internal software attributes.
• b) Quality in use characteristics: effectiveness, productivity, safety and satisfaction. Quality in use is the combined effect for the user of the six software product quality characteristics.

Parts 2 and 3 of ISO 9126 deal with external and internal quality metrics respectively. Part 4 deals with measurement of quality in use.

ISO 9241-1 (1997) Ergonomic requirements for office work with visual display terminals (VDTs) - General Introduction

This part introduces the multi-part standard ISO 9241 for the ergonomic requirements for the use of visual display terminals for office tasks and explains some of the basic underlying principles. It provides some guidance on how to use the standard and describes how conformance to parts of ISO 9241 should be reported.

ISO 9241-2 (1992) Guidance on task requirements

This part deals with the design of tasks and jobs involving work with visual display terminals. It provides guidance on how task requirements may be identified and specified within individual organisations and how task requirements can be incorporated into the system design and implementation process.

ISO 9241-3 (1993) Visual display requirements

Note: Coming ISO 9241-300 series standards are superseding this part.

This part specifies the ergonomics requirements for display screens which ensure that they can be read comfortably, safely and efficiently to perform office tasks. Although it deals specifically with displays used in offices, it is appropriate to specify it for most applications that require general purpose displays to be used in an office-like environment.

ISO 9241-4 (1998) Keyboard requirements

Note: Coming ISO 9241-400 series standards are superseding this part.

This part specifies the ergonomics design characteristics of an alphanumeric keyboard which may be used comfortably, safely and efficiently to perform office tasks. Keyboard layouts are dealt with separately in various parts of ISO/IEC 9995: 1994 Information Processing - Keyboard Layouts for Text and Office Systems.

ISO 9241-5 (1998) Workstation layout and postural requirements

This part specifies the ergonomics requirements for a Visual Display Terminal workplace which will allow the user to adopt a comfortable and efficient posture.

ISO 9241-6 (1999) Environmental requirements

This part specifies the ergonomics requirements for the Visual Display Terminal working environment which will provide the user with comfortable, safe and productive working conditions.

ISO 9241-7 (1998) Display requirements with reflections

Note: Coming ISO 9241-300 series standards are superseding this part.

This part specifies methods of measurement of glare and reflections from the surface of display screens, including those with surface treatments.

ISO 9241-8 (1997) Requirements for displayed colours

Note: Coming ISO 9241-300 series standards are superseding this part.

This part specifies the requirements for multicolour displays which are largely in addition to the monochrome requirements in Part 3.

ISO 9241-9 (2000) Requirements for non-keyboard input devices

Note: Coming ISO 9241-400 series standards are superseding this part.

This part specifies the ergonomics requirements for non-keyboard input devices which may be used in conjunction with a visual display terminal. It also includes a suggestion for a user-based performance test as an alternative way of showing conformance. The standard covers such devices as the mouse, trackball and other pointing devices, but it does not address voice input.

ISO 9241-110 (2006) Dialogue principles [previously ISO 9241-10 (1996)]

This part deals with general ergonomic principles which apply to the design of dialogues between humans and information systems: suitability for the task, suitability for learning, suitability for individualisation, conformity with user expectations, self descriptiveness, controllability, and error tolerance.

ISO 9241-12 (1998) Presentation of information

This part contains specific recommendations for presenting and representing information on visual displays. It includes guidance on ways of representing complex information using alphanumeric and graphical/symbolic codes, screen layout, and design as well as the use of windows.

ISO 9241-13 (1998) User guidance

This part provides recommendations for the design and evaluation of user guidance attributes of software user interfaces including Prompts, Feedback, Status, On-line Help and Error Management.

ISO 9241-14 (1997) Menu dialogues

This part provides recommendations for the ergonomic design of menus used in user-computer dialogues. The recommendations cover menu structure, navigation, option selection and execution, and menu presentation (by various techniques including windowing, panels, buttons, fields, etc.).

ISO 9241-15 (1998) Command language dialogues

This part provides recommendations for the ergonomic design of command languages used in user-computer dialogues. The recommendations cover command language structure and syntax, command representations, input and output considerations, and feedback and help.

ISO 9241-16 (1999) Direct manipulation dialogues

This part provides recommendations for the ergonomic design of direct manipulation dialogues, and includes the manipulation of objects, and the design of metaphors, objects and attributes. It covers those aspects of Graphical User Interfaces that are directly manipulated, and not covered by other parts of ISO 9241.

ISO 9241-17 (1998) Form-filling dialogues

This part provides recommendations for the ergonomic design of form filling dialogues. The recommendations cover form structure and output considerations, input considerations, and form navigation.

ISO 9241-151 (2008) Guidance on World Wide Web user interfaces

Provides a large number of specific principles for designing web site interfaces. These are divded up into: high-level design decisions and design strategy, content design, navigation, and content presentation.

ISO 9241-171 (2008) Guidance on software accessibility

Provides guidance on achieving a high level of accessibility in software user interfaces at work, in the home, in education and in public places. It covers issues for people with a broad range of physical, sensory and cognitive abilities, as well as the elderly and those with temporary disabilities.

Other relevant standards:

• ISO 6385 Ergonomic principles in the design of work systems
• ISO 11064 Ergonomic design of control centres
• ISO 13406 Flat panel display ergonomic requirements
• ISO TS 16071 Guidance on accessibility of human-computer interfaces
• ISO 14915 Multimedia user interface design - Software ergonomic requirements
• ISO 20282 Ease of operation of everyday products
• ISO/IEC 10741-1 Dialogue interaction - Cursor control for text editing
• ISO/IEC 11581 Icon symbols and functions
• ISO/IEC 15910 Software user documentation process
• ISO/IEC 25062 Common Industry Format (CIF) for usability test reports
• ISO/IEC 62366 Application of usability engineering to medical devices

3. Standards dealing with the product development process

ISO 9241-210 (2010) Human-centred design for interactive systems [previously ISO 13407 (1999)]

This standard provides guidance on human-centred design activities throughout the development life cycle of interactive computer-based systems. It is a tool for those managing design processes and provides guidance on sources of information and standards relevant to the human-centred approach.

Human-centred design is described as a multidisciplinary activity, incorporating human factors and ergonomics knowledge and techniques with the objective of enhancing effectiveness and efficiency, improving human working conditions, and counteracting possible adverse effects of use on human health, safety and performance.

There are four essential user-centred design activities which should be planned for and undertaken in order to incorporate usability requirements into the development process. These are:

• understand and specify the context of use
• specify the user requirements
• produce design solutions to meet user requirements
• evaluate the designs against requirements

The activities are carried out in an iterative fashion, with the cycle being repeated until the particular usability objectives have been attained. The plan should identify how these activities can be integrated with other development activities, as well as people responsible for them.

Understand and specify the context of use

This should address the following important aspects:

• the characteristics of the intended users
• the tasks the users will perform
• the environment in which users will use the system

Specify the user requirements

This looks at user and organisational requirements in relation to the context of use description (1), and it should:

• Identify the range of relevant users and other personnel in the design
• Provide a clear statement of the human-centred design goals
• Set appropriate priorities for the different requirements
• Provide measurable benchmarks against which emerging designs can be tested
• Be confirmed by the users or those representing their interests in the process
• Include and statutory or legislative requirements
• Be adequately documented

Produce design solutions

This consists of the following:

• Develop outline design proposals with multi-disciplinary input
• Make the design solution(s) more concrete using simulations, mock-ups, etc.
• Show the design solution(s) to users and allow them to perform/simulate tasks
• Iterate the process until design objectives are met

Evaluate designs against requirements

This is an essential step which assesses whether user and organisational objectives have been met and provides feedback which can be used to improve design. There are a variety of evaluation methods, varying in their formality, rigour and user involvement - the best method(s) will depend on the nature of the product being developed, finances, and time constraints.

ISO TR 18529 (2000) Ergonomics of human-system interaction - Human-centred lifecycle process descriptions

This Technical Report contains a structured and formalised definition of the human-centred processes described in ISO 13407:

• HCD.1 Ensure HCD content in system strategy
• HCD.2 Plan and manage the HCD process
• HCD.3 Specify the user and organisational requirements
• HCD.4 Understand and specify the context of use
• HCD.5 Produce design solutions
• HCD.6 Evaluate designs against requirements
• HCD.7 Introduce and operate the system

The Usability Maturity Model in ISO TR 18529 can be used in conjunction with ISO 15504 Software process assessment to assess the capability of an organisation to carry out user-centred design by rating each HCD process on the scale: Incomplete, Performed, Managed, Established, Predictable and Optimising.