Who is the biggest and richest?

Does China have a larger economy than the U.S.? Is India, Germany or Japan the world's third-largest economic power? How many minutes of labor does it take for the average worker to buy a Big Mac? These may seem like simple and straightforward questions, but the answers are surprisingly complex. Organizations such as the International Monetary Fund, the World Bank, the United Nations and others also have large research staffs searching for better ways to measure the world economy.