In the first quarter of 2008, Click Forensics announced that click fraud has decreased across Google and Yahoo to 27.8% (from 28.3% in Q4 2007).
Is that a number to be worried about? As Barry says on Search Engine Land, these numbers may not account for discounted questionable clicks. Google has said before that click fraud only accounts for 0.02% of clicks.
Meanwhile, forum members believe that the report by Click Forensics may be misleading. After all, they are a traffic quality management firm and as such "has an interest in reporting exagerrated click fraud rates," according to martinibuster. He says that if the numbers were in actuality this high, "I am certain we'd hear about it in the AdWords forum." After all, that translates to millions of dollars lost.
Forum discussion continues at WebmasterWorld.