Last week when visiting Google, I had a long background discussion with Shuman Ghosemajumder about click fraud issues. Shuman is Google's business product manager for trust and safety. I'll follow up on some of our discussion as I'm able to get some material cleared. But one of the most fascinating things was his explanation on how some third party auditing firms don't appear to be matching up estimated fraud figures with refunds or even actual clicks registered by advertisers.

Some of what he explained is now covered in two blog posts up on his personal blog: Why Third-Party Click Fraud Estimates Don't Add Up and Why Third-Party Click Fraud Estimates Don't Add Up - Part 2. The second part especially gets into a big issue now with Google -- that back button actions in a browser appear to be registered by some firms as a further "paid" click, when they are not.

Give the posts a read. As I said, I expect to be coming back to the issue in more depth in the future. Both, of course, have come out in reaction to yesterday's news from Click Forensics that click fraud is at an all time high, based on its network.