A WEAK currency, despite its appeal to exporters and politicians, is no free lunch. But it can provide a cheap one. In China a McDonald’s Big Mac costs just 14.5 yuan on average in Beijing and Shenzhen, the equivalent of $2.18 at market exchange rates. In America the same burger averages $3.71. That makes China’s yuan one of the most undervalued currencies in our Big Mac index, which is based on the idea of purchasing-power parity. This says that a currency’s price should reflect the amount of goods and services it can buy. Since 14.5 yuan can buy as much burger as $3.71, a yuan should be worth $0.26 on the foreign-exchange market. At just $0.15, it is undervalued by about 40%. The tensions caused by currency misalignments prompted Brazil’s finance minister to complain last month that his country was a potential casualty of a “currency war”. The Swiss, who avoid most wars, are in the thick of this one. Their franc is the most expensive currency on our list.

http://www.economist.com/node/17275912

以上是Economist一篇文章的观点。文章认为，RMB被低估了40%，可笑的是他按照的是中美两国McDonald的Burger来计算。摆明是满口诡辩。作者为什么不敢将中美两国的工资水平加进去呢？一时找不到具体数据，但可以肯定的是，中国工人一小时的工资要远低于美国，按照成思危先生的说法，中国的劳动力成本不到美国的4%，那么上文作者的观点就一点站不住脚了。