Rafer's team at MyBlogLog has just added a neat twist to their service that may well provide an interesting window into exactly how big a problem clickfraud is, at least from Google's perspective. A few days ago, MBL figured out how to track clicks in an iframe, which means they can now track the number of times people click on Adsense ads. Now, a blogger who is signed up for Adsense and MyBlogLog can simply compare their Google report to their MBL report, and voila - the difference should be the "clickfraud discount".
I spoke to one friend (as Google's T&C's prohibit the sharing of data, this person understandably wants to remain anonymous), and learned that Google's number of clicks was 25% of the number reported by MBL over a two-day period. Now, it's possible that MBL's system has some kinks to work out, but if these numbers stand up, this is an astonishing number.
Google has faced criticism in the past for the opacity of its reporting to Adsense publishers. We'll see if MBL can get even more info, and potentially automate its auditing functions through an API (now there's a mashup that people would pay for)...and we'll see if that will result in some additional transparency from Google.
Which would be nice.
More info on the MyBlogLog Blog, where you will see that Adsense holds the #1, #4 and #5 highest positions on the worldwide "most clicked" list across all MBL sites. The three positions result from the different unit sizes, which render as different URLs.
Disclosure: Rafer is a co-founder and director of Mashery, a partner in various other enterprises along the way, and a good friend.