Google corrects some misinformation, which I, and many others in the SEM community, were pretty skeptical about yesterday:

“I never said that our click fraud rate is less than 2%. Instead, what I said is that the quantity of invalid clicks which we detect as a result of reactive investigations is a “negligible proportion” of the total number of invalid clicks…. So what is our overall “click fraud rate”? As noted in the diagram in the story, it is virtually impossible to know the intent of every click. However, we can do a very effective job using statistical techniques to detect potentially malicious behavior, and the total number of invalid clicks we detect – whether for suspected malicious or non-malicious intent – is in the single digit percentages. So third-party estimates which say that click fraud is 15% or higher appear to clearly be substantial exaggerations.“