David Cancel, the CTO of the web market research firm Compete Incorporated, raised eyebrows at the Open Data 2007 Conference in New York when he revealed that many Internet service providers sell the clickstream data of their users. Clickstream data includes every web site visited by each user and in which order they were clicked.

The data is not sold with accompanying user name or information, but merely as a numerical user value. However, it is still theoretically possible to tie this information to a specific ISP account. Cancel told Ars that his company licenses the data from ISPs for millions of dollars. He did not give a specific figure about what this broke down to in terms of dollars per ISP user, although someone in the audience estimated that it was in the range of 40¢ per user per month—this estimate was erroneously attributed to Cancel himself in some reports on the event. Cancel said that this clickstream data is “much more comprehensive” than data that is normally gleaned through analyzing search queries.