In the summer of 2003, The New York Times Magazine sent Stephen J. Dubner, an author and journalist, to write a profile of Steven D. Levitt, a heralded young economist at the University of Chicago. Levitt was not remotely interested in the things that interest most economists. Instead, he studied the riddles of everyday life-from cheating to crime to child-rearing-and his conclusions turned the conventional wisdom on its head.

Levitt and Dubner then collaborated on Freakonomics, a book that gives full play to Levitt''s most compelling ideas. Through forceful storytelling and sharp insight, it reminds us all that economics is, at its root, the study of incentives-how people get what they want or need, especially when other people want or need the same thing. Among the questions it answers: Which is more dangerous, a gun or a swimming pool? If drug dealers make so much money, why do they still live with their mothers? What makes a perfect parent? And, of course: What do schoolteachers and sumo wrestlers have in common? (Answer: they both cheat.)

Now this cultural blockbuster comes to trade paperback with exclusive extras- including a new preface, five Freakonomics columns from The New York Times Magazine, an exclusive author Q & A and a sneak preview of Superfreakonomics.