[vash_stampy]

I like your stock market insider information analogy because it illustrates the flaw in Google's experiment very well. And very few people seem to realize it. I need to modify it slightly though to make it more analogous.

Suppose your financial advisor (Google) was suspecting that someone (Bing) was stealing their confidential financial reports on stocks. Suppose your financial advisor told you (Google Engineer) to buy 100 random shares (search and click on 100 specific search terms) and see if the suspect (Bing) acted on it.

Even if the suspect bought 100% of the shares (Bing indexes all the search terms with the irrelevant links), you still haven't proven the suspect is stealing information from the financial advisor because there's more than one source this information could have come from. It could have come from you (Google Engineer doing the clicking) or it could have come from your financial advisor (Google itself). A way to solve this issue is if you (Google engineer) had another financial advisor (another website) which told you to buy certain companies. If the suspect didn't act on those shares then you would have MUCH more conclusive evidence that the suspect was stealing from the financial advisor represented by Google.