Krugman was awarded a B.A. from Yale University in 1974 and a Ph.D. from MIT in 1977. He went on to teach at both his alma maters as well as at Stanford University before becoming a professor of economics and international affairs at Princeton University. A prolific writer, from 1999 he has been an op-ed columnist for The New York Times. Among his books are the essay collection The Great Unraveling: Losing Our Way in the New Century (2003), which criticized the administration of Pres. George W. Bush (Bush, George W.), and The Conscience of a Liberal (2007). In addition to the Nobel Prize, Krugman received many honours, including the 1991 John Bates Clark medal, awarded to economists under age 40.