In fall of 1999, a relatively small airline found that traffic on its website was exceeding all expectations. However, very few visitors were enrolling in the frequent flyer program. A usability testing company was hired to bring people from diverse backgrounds into a testing lab, where they were encouraged to think aloud while they were videotaped as they used the site. The subjects were asked to enroll in the airline's frequent flyer program. Soon the problem became apparent. When asked to enter a date of birth, the user was presented with a blank field, which did not specify that the user needed to enter four digits for the year. The majority of test users entered two numbers and received an error message. The error message did not provide information about how to correctly enter the year. As a result, users gave up in frustration. This example highlights a situation in which the nature of the problem became apparent only after a close observation of the users.
Once identified, the problem was easy to solve. Interfaces that are logical and clear to developers are not always logical and clear to end users. That's why usability testing is important.

The primary goals of usability testing are to verify the following:

1. The information provided by the site is the information that users are seeking.
2. The information architecture of the site allows users to find the information they are seeking in an efficient manner.
3. The business objectives of the site and the desire to present additional information (e.g., promotions of products and services) are effective, without interfering with a user's primary reason for being at the site.
4. Navigational elements help users orient themselves and move throughout the information space.

Jakob Nielsen notes that testing is often believed to be very costly and complex. However, according to Nielsen, the best results come from testing with no more than five users. His argument is that as soon as you collect data from a single test user, you gain considerable insight and are likely to identify roughly one third of all the existing problems with the usability of the site. When you test the second user, you discover many of the same things you discovered with the first user, but you also encounter some new information. With each subsequent user, you find some new information, but as you add more and more users, you learn less and less because you keep seeing the same things again and again. Refer to the resource page if you want to read Nielsen's entire argument on the use of only 5 testers.
It may make sense to do iterative testing in which you test one group of five users, make modifications, test a second group of five users, make any additional modifications, and then test a third group of five users. According to Nielsen,

the ultimate user experience is improved much more by three tests with 5 users than by a single test with 15 users.

The most common method of usability testing is to conduct informal tests. Other often-used approaches include the use of low-fidelity (e.g., paper) prototyping, expert usability evaluations, tests of the navigational design, and user analysis. In addition, new online approaches are being used. For example, an approach that tracks eye movements and has been used for many years for looking at print-based materials is now being used online. A significant finding of the online research is that users tend to look first and most intently at text. Unlike readers looking at printed materials, readers looking at online materials tend to gloss over photos and images in search of meaningful textual information. In the next lesson you will learn how to evaluate and compare competing Web sites.

Click the Quiz link below to check your knowledge of functionality and usability testing.
Website Usability- Quiz

Click the Exercise link below to apply what you have learned about usability requirements.
Usability Testing - Exercise