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What's happening with usability?
by Juan C. Dürsteler [message nº 68]

Usability is indispensable for the design of a good web site. Nevertheless not all the rules are infallible. Common sense is the tool of choice. 

This week I received Jakob Nielsen and Marie Tahir's new book about homepage usability. The book is titled "HomePage Usability: 50 websites deconstructed" and deals with (as you surely have already imagined) what makes the most important page of any website usable. 

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Cover of "Home Page Usability" by Jakob Nielsen and Marie Tahir.  
(Click on the image to enlarge it)
The book has a carefully crafted design and a simple and clear structure composed of two well differentiated parts. 

In the first part, 113 guidelines are presented, grouped in sections dealing with topics ranging from how to communicate the goal of the site to representing numbers and stock exchange values. In this part  many interesting statistics regarding logo sizes, location of the search box, navigation elements and so on are presented as well.

The second part is devoted to the dissection of the homepages of 50 relevant web sites among which you can find the ones of Amazon, E-bay, Disney and Exxon-Mobil just to cite a few. A commendable book, at least as reference material and to exercise a reflection on what is important when designing a homepage. It's very good as a checklist against which to contrast our design.

What's true is that usability is not an exact science, as is the case with almost everything that has something to do with human behaviour. 

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Cover of "Don't Make Me Think" by Steve Krug.
(Click on the image to enlarge it)
As Steve Krug remarks in his excellent book "Don't Make me Think", usability is a matter "of common sense and anybody interested in it can learn how to do it". Interestingly enough his company is called "Advanced Common Sense". 

There exists some controversy around Jakob Nielsen, maybe due to his inclination to present his interesting ideas on usability as indisputable truths. There's no doubt that Nielsen is one of the top authorities on the topic. His conclusions and guidelines are full of substance, since they are based on many years of experience.

Nevertheless an interview made with Jared M. Spool, another of the usability experts, by John S. Rhodes for Webword.com, questions the usability of usability itself.

In the article, titled "The Usability of Usability", Spool reveals that some of what we consider as well established ideas are disputable. You can see the interesting series of "Best Practices" reports at his company's web site. The company is called User Interface Engineering.

For instance, Nielsen states that 10 seconds is the maximum allowable download time for a page. The research carried out by Spool shows that download time is not directly associated with a website's usability. Moreover, when the users were asked to rate the speed of a web site, the assessment was strongly correlated to whether they completed their tasks, instead of the download time.

According to Nielsen you only need 5 users to catch 85% of the usability problems of a web site, but Spool's research indicates that in some cases after testing 18 users less than 50% of the errors were pointed out.

The variability of human perception, the multiplicity of factors that play a part in a test with real users and the diversity of styles and web sites makes it advisable to weigh up any "rule of thumb" with extreme caution. The construction of a scientific theory about Usability is still years away.

So then, usability is a field in its early stages, where most of the rules and advice is useful, but still don't replace common sense. 

Denying the importance of usability and not taking it into account is a capital sin in today's Web. Not using the filter of common sense and experience, is nonsense.

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