World Bank, which published updated statistics on the economic output of 146 countries. China’s economy, said the bank, is smaller than it thought. About 40% smaller. China, it turns out, isn’t a $10-trillion economy on the brink of catching up with the United States. It is a $6-trillion economy, less than half our size.
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Unfortunately, comparing hundreds and even thousands of prices in almost 150 economies all over the world is a difficult thing to do. Concerned that its purchasing-power-parity numbers were out of whack, the World Bank went back to the drawing board and, with help from such countries as India and China, reviewed the data behind its GDP adjustments.

It learned that there is less difference between China’s domestic prices and those in such countries as the United States than previously thought. So the new purchasing-power-parity adjustment is smaller than the old one — and $4 trillion in Chinese GDP melts into air.