The Economist regularly publishes the Big Mac index to examine the validity of purchasing power parity. If purchasing power parity holds, a consumer should be able to take the same amount of money required to buy a Big Mac in the U.S. and buy a Big Mac in any other country. What are the reasons purchasing power parity may not hold? If the U.S. dollar depreciates against the euro and purchasing power parity holds, would a Big Mac in Europe become more or less expensive? Why? If purchasing power parity doesn't hold, does an American tourist in Europe pay more or less for a Big Mac? Why?