Is Big Brother Google watching you?

[ReviewGolf.com]

Is it just me of does Google employ some technology that lets them know more then we bargain for? Below is a paragraph from an email cheerfully sent by Google the other day. Please someone explain to me how does Google analyze the data in bold and where do they get it from? Or is it just their wishful thinking?

How smart pricing works
We are constantly analyzing data across our network, and if our data shows that a click is less likely to turn into business results (e.g. online sale, registration, phone call, newsletter sign-up), we may reduce the price you pay for that click. You may notice a reduction in the cost of clicks from content sites.