According to an AP report,
Fair Isaac’s preliminary data shows that 10 to 15 percent of online
advertising traffic is "pathological," indicating a likelihood of click
fraud, said Joseph Milana, the company’s chief scientist of research
In a just-issued press release, Fair Isaac is saying this 10 to
15-percent figure is referring to billed clicks, which puts these
estimates much, much higher than those coming from the search engines,
or from third-party reports from Click Forensics and others.