Suppose the user was on search engine A and then goes to site B. I believe Hitwise has no way of knowing whether the user clicked on a link in the search result

Suppose the user was on search engine A and then goes to site B. I believe Hitwise has no way of knowing whether the user clicked on a link in the search results to go to site B vs. just going to site B on their own. As far as how the data was gathered, Hitwise gets clickstream data from ISPs: http://www.hitwise.com/us/about-us/how-we-do-it http://www.hitwise.com/us/about-us/how-we-do-it