Here’s an interesting article regarding recently updated GDP calculations:

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. For the foreseeable future, China will have far less money to spend on its military and will face much deeper social and economic problems at home than experts previously believed.

What happened to $4 trillion in Chinese gross domestic product?

Statistics. When economists calculate a country’s gross domestic product, they add up the prices of the goods and services its economy produces and get a total — in dollars for the United States, euros for such countries as Germany and France and yuan for China. To compare countries’ GDP, they typically convert each country’s product into dollars.

The simplest way to do this is to use exchange rates. In 2006, the World Bank calculated that China produced 21 trillion yuan worth of goods and services. Using the market exchange rate of 7.8 yuan to the dollar, the bank pegged China’s GDP at $2.7 trillion.

That number is too low. For one thing, like many countries, China artificially manipulates the value of its currency. For another, many goods in less developed economies such as China and Mexico are much cheaper than they are in countries such as the United States.

To take these factors into account, economists compare prices from one economy to another and compute an adjusted GDP figure based on “purchasing-power parity.” The idea is that a country’s GDP adjusted for purchasing-power parity provides a more realistic measure of relative economic strength and of living standards than the unadjusted GDP numbers.

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.

Continue reading: “The great fall of China”