5.2 Usability principles
Usability as a field of study has grown rapidly with the spread of computers, the Web, mobile phones and other portable IT devices. Although there are some basic principles of good, usable design, there are no rules that guarantee a good design. In this respect design for usability is like other branches of design, such as industrial design, book design or interior design.
Usability design draws on ideas from psychology, ergonomics, typography and so on, and makes extensive use of feedback from users. Feedback is gathered using various techniques, such as questionnaires, observation of users, interviews and recordings of users in action. Recordings of users can take many forms also, for example timing, video recording, recording users' spoken commentaries, and tracking software that records all the key strokes made by a user.
Like virtually all areas of design, usability design is (or should be) iterative. That is, a prototype is tried, evaluated, modified in the light of evaluation, tried again, and so on. It is especially important to try a prototype with the kind of people who will use the finished product. Sara Bly, who designs and evaluates interfaces, says:
Recently I was asked to design and evaluate an application for setting up personal preferences and purchasing services on the web. I was told it would be hard to test the interface 'in the field' because it was difficult to get a 45–60 minute test period when the user wasn't being interrupted. When I pointed out that interruptions were normal in the environment in which the product would be used and therefore should occur in the evaluation too, the client looked aghast. There was a moment of silence as he realised, for the first time, that this hadn't been taken into account in the design and that the interface timed out [that is, closed down after a period of inactivity, with loss of data already entered] after 60 seconds. It was unusable because the user would have to start all over again after each timeout.
This focus on the users of the system is an example of the human-centred design (HCD) approach. The HCD approach is intended to ensure that aims of the interface or service are fulfilled for real users. The term 'users' is understood to mean not just the customers or members of the public who use the interface for a particular service (sometimes referred to as end users), but also the people who have to operate and maintain the system.
The principles of good design for e-government systems are not significantly different from those for other systems. For instance, Cabinet Office (2003), Quality Framework for UK Government Website Design, offers these pieces of advice (among others):
A good government website should have some content that has been specifically written for the Web […][and] should not simply repeat printed brochures […]
Writing for the Web is a specific skill.
Cabinet Office (2003), p. 30.
Jakob Nielsen, who has written extensively about usability, similarly says that writing for the Web is very different from writing for the page:
People rarely read Web pages word by word; instead, they scan the page, picking out individual words and sentences. […] As a result, Web pages have to employ scannable text […]
Activity 26 (self-assessment)
The following two pieces of text are directed at managers of an e-government project, and offer advice on dealing with web designers. Which would be better suited for online presentation, and why?
'A web designer should make it clear from the start what they will need you to do to quickly and effectively build your website. Content will be the major requirement. Indeed, it is often this aspect of putting together a website that takes the greatest amount of time, as the content must be collated and optimised for the Web. Ensure you have your content completed to the deadline you have agreed. This will ensure the designer/agency has no excuse concerning the completion of the project on time.' (Cabinet Office, 2003, p. 44)
A web designer should make it clear what you need to do. Content will be your major contribution to the site.
Assembling content often takes longer than anything else. This isl because it needs to be:
optimised for the Web.
Be sure to observe your deadlines, so that the designer/agency cannot blame you if the project runs late.
Text 2 is much more scannable (to use Nielsen's term) than 1. It is easier to take in text 2 at a glance than text 1. This is because the paragraphs are shorter, the sentences are shorter (and simpler), and important sequences of ideas are listed ('collated' and 'optimised for the Web').
Nielsen's reason for advocating scannable text is not just because it is easier to read, but because it helps the viewer decide whether the text is worth reading. This is important because Web use is as much about deciding whether a page looks useful as it is about reading what is on the page. As further aids to scannability, Nielsen advises the use of:
highlighted keywords (hypertext links serve as one form of highlighting; typeface variations and colour are others)
meaningful sub-headings (not 'clever' ones)
one idea per paragraph (users will skip over any additional ideas if they are not caught by the first few words in the paragraph)
the inverted pyramid style, starting with the conclusion
half the word count (or less) than conventional writing
The price paid for concise web pages is loss of context and detail, but these can sometimes be supplied in other ways, for instance by headings, clear links and highlighted keywords, all of which Nielsen advocates.
The authors of Quality Framework for UK Government Website Design point to the importance of a search engine:
[A]n effective site-specific search engine is crucial to most good government websites.
Cabinet Office (2003), p. 33
Once again, this advice agrees with Nielsen's view of good practice:
Search is the user's lifeline when navigation fails. Even though advanced search can sometimes help, simple search usually works best, and search should be presented as a simple box, since that's what users are looking for.
In fact, for many users a search facility is not a second choice, to use when navigation fails, but a first choice that is often quicker and simpler than the navigation facilities.
Nielsen has at various times summarised his thoughts on usability in a list of principles. Here is one such list, slightly simplified by Preece et al. (2002).
Visibility of system status. Always keep users informed about what is going on, through providing appropriate feedback within reasonable time.
Match between system and the real world. Speak the users' language, using words, phrases and concepts familiar to the user, rather than system-oriented terms.
User control and freedom. Provide ways of allowing users to easily escape from places they unexpectedly find themselves, by using clearly marked 'emergency exits'.
Consistency and standards. Avoid making users wonder whether different words, situations, or actions mean the same thing.
Help users recognise, diagnose, and recover from errors. Use plain language to describe the nature of the problem and suggest a way of solving it.
Error prevention. Where possible prevent errors occurring in the first place.
Recognition rather than recall. Make objects, actions, and options visible.
Flexibility and efficiency of use. Provide accelerators [for example, keyboard shortcuts] that are invisible to novice users, but allow more experienced users to carry out tasks more quickly.
Aesthetic and minimalist design. Avoid using information that is irrelevant or rarely needed.
Help and documentation. Provide information that can be easily searched and provides help in a set of concrete steps that can easily be followed.
Nielsen's principles apply to all types of computer interface, for example the interfaces to operating systems, word processors, calculators and so on, not just web interfaces.
Principles like these give you an evaluative framework, but they are not in themselves a quick tool for evaluating an interface. For instance, an interface that falls short on two of these principles is not automatically better than one that falls short on three. The evaluation has to take into account the way the interface is used, which will probably (among other things) lead to some principles counting for more than others.