What does usability testing measure?

Usability testing is designed to measure a combination of factors that affect the users' ability to accomplish tasks at the site.

Some of the common factors are:

• ease of learning,
• efficiency of use,
• memorability,
• error frequency and severity, and
• user satisfaction.

Web resources can be evaluated using a variety of methods, including the collection of website statistics, the analysis of feedback provided via phone or email, and structured interviews with users. Testing websites with individuals or groups of users can be very effective.

Testing can provide useful information that can be used to make highly effective modifications to web resources. User testing can generally be done with minimal resources and produce useful results. Other methods of evaluation can, however, supplement the results of user testing and result in even more accurate assessments of web resource effectiveness. Alternative methods may also include expert evaluation, heuristic review, usability walk-through, surveys and monitoring software.]

User testing involves members from the target audience working through a set of tasks using the web resource being evaluated. Usability-testing sessions may be conducted in a usability laboratory, at the person's desk or in a room set up to resemble a usability laboratory. There is normally one person per test session, with the session lasting from 30 minutes to an hour, although longer sessions may be conducted. However, due to OH&S requirements there must be a 15-minute break every 45 minutes.

The purpose of the usability test is to evaluate, from the user's perspective, the ease of use and intuitiveness of the resource. As users test the resource, they provide feedback on it, advising about what they like and dislike and about any difficulties they may have while using the site. This information can be used to revise the site in development or redesign.

http://www.agimo.gov.au/publications/2004/06/toolkit/testing/process