Website Usability Guidelines

About Usability Testing (3 of 6)

Do you need a lab to do usability testing? No. You can do usability testing in either a formal or informal setting. In any type of setting, your methodology can also range from formal to informal.

How many participants are needed for a usability test? It depends. A typical range is from 8 to 12 participants for each test. If each user works with you for an hour, that means one or two days of testing.

You might need only 4 to 6 people to help you find serious problems, if you:

• Are doing paper prototypes or are in early development
• Plan several rounds of testing throughout development
• Have a fairly homogenous user population

If you have different potential user groups (for example, physicians, patients, researchers), try to include representatives of all these groups. If you are likely to have users with a range of Web or computer experience, try to include both less experienced and more experienced users.

If you want to conduct formal quantitative testing on your products or systems, you'll need more people to derive statistical results. For diagnostic usability testing, 6 to 8 users are usually enough to uncover the major problems in a product.

If you do repeated usability testing over the course of developing the website, many users will participate in testing one or another version of the emerging site. Thus, while you may have fewer than 10 participants in each usability test, you may have 15 to 30 people who have tested some version of the site before it is launched.