The Economist is out with its annual Big Mac index, a "lighthearted" look, the magazine is always careful to note, at currency values and purchasing power parity. The idea is that the Big Mac is a commodity -- the same in Beijing as in Barcelona -- so differences in Big Mac prices around the world should tell us something about currency distortions. It's not that simple, but this year's index surely shows how the Chinese have manipulated and underpriced the yuan to goose their exports. Says the press release:

So which countries has the foreign-exchange market blessed with a cheap currency, and which has it burdened with a dear one?

The dollar buys the most burger in Asia. A Big Mac costs 12.5 yuan in China, which is $1.83 at today’s exchange rate, around half its price in America. Other Asian currencies, such as the Malaysian ringgit and Thai bhat, look similarly undervalued. Businesses based in continental Europe have most to be cheesed off about. The Swiss franc remains one of the world’s dearest currencies. The euro is almost 30% overvalued on the burger gauge. Denmark and Sweden look even less competitive.

However, The Economist says: “The markets have been kindest to British exporters. A year ago the pound was overvalued by more than a quarter on the Big Mac gauge. Now it is close to its fair value against the dollar and looks cheap against the euro. That shift has upset some other EU countries that had relied on selling to spendthrift British consumers. But after years of struggling with an overvalued currency, British firms will feel they deserve a little mercy.”