China is already number one. So says Arvind Subramanian:
When the presidents of China and the United States meet next week in Washington, neither will likely be aware that, measured in terms of purchasing power, it is Hu Jintao not Barack Obama who represents the world’s largest economy. Some time in 2010, the Chinese economy overtook that of the United States. My calculations of GDP for 2010—which of course are subject to the uncertainty associated with all such exercises—are based on new estimates of GDP that will soon be published by the Penn World Tables (PWT) under the guidance of Professor Alan Heston at the University of Pennsylvania.