Steven D Levitt is an American economist known for his work in crime. He was a winner of the 2003 John Bates Clark Medal, and is currently a professor at the University of Chicago. Levitt co-authored the best-selling book Freakonomics, and its sequels Superfreakonomics and Think Like a Freak. He co-founded TGG Group, a business and philanthropy consulting company, and in 2006 was chosen as one of Time magazine’s “100 people who shape our world.”