Detecting Hit Shaving in Click-Through Payment Schemes

A web user "clicks through" one web site, the referrer, to another web site, the target, if the user follows a hypertext link to the target's site contained in a web page served from the referrer's site. Numerous click-through payment programs have been established on the web, by which (the webmaster of) a target site pays a referrer site for each click through that referrer to the target. However, typically the referrer has no ability to verify that it is paid for every click-through to the target for which it is responsible. Thus, targets can undetectably omit to pay referrers for some number of click-throughs, a practice called hit shaving. In this paper, we explore simple and immediately useful approaches to enable referrers to monitor the number of click-throughs for which they should be paid.