In this table, we consider the usability measured for users with disabilities to be 100% the usability experienced by the control group has been normalized relative to that level. The following table compares the control group's performance with an average of the two user groups with disabilities. At the same time, the tasks were not overly easy, as many members of the control group did not complete tasks, and the average task performance time was more than seven minutes. Usually, success rates in Web usability studies range from 40% to 60%, so the current average of 78% for the control group probably indicates that the test tasks were a little bit easier than those in our other studies. The control group's success rate was 78%, which is considerably higher than the success rates we've found in most of our other studies. The following table shows four usability metrics averaged across these tasks for three groups of users: people using screen readers (mainly users who were blind), people using screen magnifiers (users with low vision), and the control group of users without disabilities. Fact-finding: Find the average temperature in Dallas, Texas in January (for this task, participants could use any site they wanted).Compare and contrast: Find the best mutual fund satisfying certain criteria on.Information retrieval: Find a bus departing from O'Hare airport to a specific address in Chicago, using.Buy an item: Purchase Janet Jackson's CD "All for You" from.We also collected measurement statistics from four tasks: As always, we learned the most from our qualitative studies, where we asked users to think out loud as they used the sites. We focused on design usability, aiming to identify which design elements slowed users down, confused them, or caused them to make errors, such as visiting the wrong part of a website. We also tested a control group of 20 users without disabilities. We recently completed a major usability study of 19 websites in the United States and Japan, observing 84 users who were either blind or had low vision or motor impairments as they performed a variety of tasks. Usability is Three Times Better for Non-Disabled Users But, just because a design is theoretically accessible, doesn't mean that it's easy to use, simple to learn, or supports efficient job performance. If you can't get at the information or services that a website or intranet offers, then you definitely can't use it either. Obviously, websites must be accessible through alternative user interface devices, such as screen readers and screen magnifiers. Sure, users with disabilities are disabled, and many must use assistive technologies to access the Web. Once we've achieved technical accessibility, our new goal must be task support and increased usability of websites and intranets for people with disabilities. We should consider these users as users: As people who have jobs to perform and goals to accomplish when they use websites and intranets. It's time we moved beyond technical accessibility when discussing how to improve the Web for users with disabilities.
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