There’s no getting away from the fact that some aspects of usability can appear fairly tedious. At a recent conference I attended I decided to observe members of the audience and measure the HTFDR (head-to-floor distance reduction). When the topic of usability standards came up, my estimate is that the HTFDR dropped from 135cm to 121cm, only to bounce back to normal when the speaker uttered the magic words: "And in conclusion…"

Why we need a standard for web usability

It’s a difficult job to make standards interesting, but it is worth considering why we need a standard for web usability.

  • Standards promote best practice. This is important in an area such as web usability that is still relatively young and contains many conflicting opinions on what makes a web site usable.
  • Standards are independent. The guidance in standards does not represent the opinion of one company or one usability guru but presents a balanced, authoritative view.
  • Standards encourage consistency. Consistency is an important factor in creating web sites that are simple to use.
  • Standards mean business. Companies can ignore your research findings but they can’t ignore standards since compliance is a mandatory requirement in many contracts (especially in the EU).

Most standards activity relevant to the web has emerged from the W3C but they have little to say about usability. Enter the International Standards Organisation (ISO). ISO are engaged in developing a new standard titled ISO/AWI 23973 "Software ergonomics for World Wide Web user interfaces". ISO has been developing ergonomics standards for over 20 years and one of their sub-committees (SC 4) is responsible for standards in the field of human system interaction. I attend one of SC 4’s working groups (WG 5) as the UK expert on behalf of the British Standards Institute.

What's in the new standard?

This new web usability standard — or more technically, "work item" as it hasn’t been approved yet — is based around a reference model that distinguishes the three domains within which design work is carried out (see the figure below.

Text description.

The ISO 23973 Reference Model


  • The process domain. This domain describes the design process used by the organisation, such as the one described in ISO 13407:1999 Human-centred design processes for interactive systems.
  • The evaluation domain. This domain contains the tools and techniques used to assess the final design, such as usability testing.
  • The design domain. This is the domain within which the designer develops the web site.

The emerging standard addresses the design domain only, so this isn’t the place to go if you are interested in usability evaluation or design process (although it does contain a handy list of references to these other areas). Where it will help is when you are involved in the nitty-gritty of design decisions and need some authoritative guidance.

The standard contains detailed guidance in four main areas:

  1. Purpose and strategy. What is the purpose of the site and how is this made clear to its users?
  2. Content and functionality. What is the site’s conceptual model? How is content organised and how should the site deal with issues such as privacy and personalisation?
  3. Navigation and interaction. How should the content be organised so that users can navigate the site easily? How will users search the content of the site?
  4. Presentation and media design. How should individual pages be designed so that people can make use of the information? How should multimedia be used?

Given the current emphasis on disability issues, you might be surprised to find that the emerging standard does not have much to say about accessibility. But this is because ISO is developing another standard specifically on this issue (ISO/AWI 16071 "Ergonomics of human-system interaction — Guidance on software accessibility").

The document is set to become a Committee Draft or CD in a few months. At that point, it is open to comment by national standards bodies.

Note added 7th July 2004: The international community have recently approved the Committee Draft and so the document has now progressed to the next stage of processing: a "Draft International Standard".

Note added 3rd July 2008: This is now an International Standard, published as ISO 9241 part 151.

About the author

David Travis

Dr. David Travis (@userfocus on Twitter) holds a BSc and a PhD in Psychology and he is a Chartered Psychologist. 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, you'll love his online user experience training course.



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