Why standards matter
With the rapid development of new user interface technologies, like Web 2.0 and mobile devices, it's tempting to claim that there's a lot more to good design than simply applying standards. Although this is certainly the case, international standards in usability still have an important role to play. This is because usability standards:
- Ensure consistency: Standards provide a consistent benchmark to help design teams avoid annoying user interface inconsistencies.
- Define good practice: There are many conflicting viewpoints about good practice in usability. Standards, especially International Standards, provide independent and authoritative guidance.
- Prioritise user interface issues: Standards are serious business and whereas many organisations pay little regard to research findings, few organisations can afford to ignore standards.
- Help organisations fulfil their legal obligations: Disability legislation and Health & Safety legislation puts a legal obligation on service providers and employers to ensure that systems provided for users are fit for purpose and meet minimum ergonomics requirements. These requirements are worded rather vaguely in the legislation and therefore meeting relevant standards is one of the best ways of demonstrating compliance.
ISO 9241: From VDTs to human-system interaction
ISO 9241 is one of the more important standards in usability. Originally titled "Ergonomic requirements for office work with visual display terminals", it was envisaged as a 17-part standard. But the interest in ISO 9241 encouraged the standards sub-committees to broaden its scope, to incorporate other relevant standards and to make it more usable. The title of the revised ISO 9241, "Ergonomics of human-system interaction", reflects these changes. The revised multipart standard is structured as a series of standards numbered in "hundreds" as follows:
- 100 series: Software ergonomics
- 200 series: Human system interaction processes
- 300 series: Displays and display related hardware
- 400 series: Physical input devices - ergonomics principles
- 500 series: Workplace ergonomics
- 600 series: Environment ergonomics
- 700 series: Application domains - Control rooms
- 900 series: Tactile and haptic interactions
Last year, 13 new parts were released. These parts are summarised below.
Part 20: Accessibility guidelines for ICT equipment and services
This part of ISO 9241 contains general recommendations to improve the accessibility of ICT equipment. The definition of "ICT equipment" is left deliberately vague, but includes mobile devices, computers and software. The standard promotes a framework for accessibility that has four steps.
- Understand and specify context of use paying particular attention to the variation of user characteristics, and the impact of task, equipment and environmental characteristics that affect accessibility.
- Specify the user requirements for accessibility.
- Produce design solutions paying particular attention to accessibility considerations.
- Evaluate accessibility design solutions of ICT equipment and services with the targeted user group.
Part 151: Guidance on World Wide Web user interfaces
This part of ISO 9241 presents detailed design principles for designing usable web sites. The standard covers five areas:
- High-level design decisions and design strategy: What is the purpose of the site and how is this made clear to its users? Who are the users and what are their goals?
- Content design: What is the site's conceptual model? How is content organised and how should the site deal with issues such as privacy and personalisation?
- Navigation and search: How should the content be organised so that users can navigate the site easily? How will users search the content of the site?
- Content presentation: How should individual pages be designed so that people can make use of the information? How should links be designed?
- General design aspects: how should you design for an international audience? How should you provide help? What download times are acceptable?
Part 171: Guidance on software accessibility
This part of ISO 9241 provides guidance on how to design accessible software. The scope is extremely broad. Unlike the W3C's Web Content Accessibility Guidelines, this standard covers all software (not just the web) and as well as the obvious home and work domains it also explicitly includes public systems, such as kiosks. Moreover, the standard uses the term "accessibility" in a very broad context, encompassing elderly users as well as users with a temporary disability (such as someone with a broken arm).
Part 300: Introduction to electronic visual display requirements
This part of ISO 9241 is an introduction to the "300" subseries, like a foreword to a book. It is very short: the main content occupies just 4 pages.
Part 302: Terminology for electronic visual displays
This part of ISO 9241 simply contains a list of definitions, terms and equations that are used by the other parts in the "300" subseries. It's no more (and no less) than a display technologist's dictionary.
Part 303: Requirements for electronic visual displays
This part of ISO 9241 establishes image quality requirements for electronic visual displays. The requirements are deliberately generic, so they apply to any kind of display, regardless of the technology used, and they cover all users and tasks.
Part 304: User performance test methods for electronic visual displays
This part of the ISO 9241 "300" subseries is quite different from the others. Although it covers visual displays, it takes a very different approach from the other parts in the subseries. The other parts focus on optical and electronic measurements of displays, whereas this part focuses on measuring how people perform when using the display: in other words, you run a (summative) usability test.
Part 305: Optical laboratory test methods for electronic visual displays
This part of ISO 9241 describes optical test methods and expert observation techniques to evaluate a visual display against the requirements in ISO 9241-303. Weighing in at around 200 pages, this is a substantial text that contains very detailed instructions on taking display measurements.
Part 306: Field assessment methods for electronic visual displays
This part of ISO 9241 will help you evaluate visual displays in the wild—for example, in offices. It is essentially a guide to ergonomic workplace assessment for visual displays.
Part 307: Analysis and compliance test methods for electronic visual displays
This part of ISO 9241 is a companion part for ISO 9241-305. Again, it runs to around 200 pages and its purpose is to help you decide if your display meets the requirements.
Part 308: Surface-conduction electron-emitter displays (SED)
This part of ISO 9241 is a technical report on a new kind of display technology called "Surface-Conduction Electron-Emitter Displays" or SED for short.
Part 309: Organic light-emitting diode (OLED) displays
This part of ISO 9241 is a technical report on a new kind of display technology called "Organic Light Emitting Diode Displays" or OLED for short.
Part 410: Design criteria for physical input devices
This part of ISO 9241 describes the critical design characteristics for input devices, namely keyboards, mice, pucks, joysticks, trackballs, touchpads, tablets, styli and touch sensitive screens. It's aimed at people who are actually designing these devices so that they take into account all the relevant ergonomic factors for their device. The standard covers a range of devices, so it's not surprising that this standard runs to over 100 pages.
If you need more information on ISO 9241, try "ISO 9241 for Beginners", a no-waffle, just-the-facts guide written by a standards expert with each part of ISO 9241 clearly explained on a single page.
About the author
Dr. David Travis (@userfocus on Twitter) is a User Experience Strategist. He has worked in the fields of human factors, usability and user experience since 1989 and has published two books on usability. David helps both large firms and start ups connect with their customers and bring business ideas to market. If you like his articles, why not join the thousands of other people taking his free online user experience course?
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