I once saw a brilliant presentation about how simple data analysis can detect credit card fraud**. The presentation showed a pattern in how people use their credit cards. Given a large number of people who had been victims of credit card fraud, this pattern showed there was just 1 store in-particular where they had all used their cards. There was no observational evidence of someone at that store stealing card details.

The first time I flew over the North Atlantic was quite an experience. Through the clouds, I could see some little white boats out sailing in the sea. It was puzzling: from 30,000 feet, those boats must have been huge for me to be able to see them at all.