Steven D. Levitt teaches economics at the University of Chicago. His idiosyncratic economic research into areas as varied as guns and game shows has triggered debate in the media and academic circles. He recently received the American Economic Association's John Bates Clark Medal, awarded every two years to the best American economist under forty. Stephen J. Dubner lives in New York City. He writes for The New York Times and the New Yorker, and is the bestselling author of Turbulent Souls and Confessions of a Hero-Worshipper. In August 2003 Dubner wrote a profile of Levitt in The New York Times magazine. The extraodinary response that article received led to a remarkable collaboration.