Introduction:
A critical problem for users of the World Wide Web is that many sites are difficult to navigate, hard to use and have confusing structure. Examples abound because the phenomenon is so widespread. Users may become lost, and they may make (or be forced to make) large leaps within a Web site (for example, returning unnecessarily to the home page) that are inconsistent with its structure. They may rely on their browser s back button as a navigational tool. They may be unable to find content and abandon the site. Obviously site authors do not frustrate their visitors intentionally. It is simply exceedingly difficult to create easy-to-use sites. A structure that seems intuitive to an author may be highly confusing to everyone else. Nor is there is any mechanism for site authors to understand at any but the most cursory level how visitors actually use the site. One way to improve usability is to conduct formal user studies and measure user performance for specific tasks, but this is too expensive for all but a few sites. A second approach is to exploit the rich instrumentation in the on-line world. This is the approach we adopt here.
tr159.pdf