Tina Rosenberg is co-writer of the New York Times' Fixes column and author, most recently, of "Join the Club: How Peer Pressure Can Transform the World." For 10 years she was a member of the New York Times editorial board writing editorials on foreign affairs. She is a contributing writer to the Times Sunday magazine. She has written two other books: "Children of Cain: Violence and the Violent in Latin America", and "The Haunted Land: Facing Europe's Ghosts After Communism", which won the Pulitzer Prize and the National Book Award.