巨无霸指数 Big Mac index
巨无霸指数（Big Mac index）是一个非正式的经济指数，用以测量两种货币的汇率理论上是否合理。这种测量方法假定购买力平价理论成立。
The Economist’s Big Mac index is based on one of the oldest concepts in international economics: the theory of purchasing-power parity (PPP), which argues that in the long run, exchange rates should move towards levels that would equalise the prices of an identical basket of goods and services in any two countries. Our “basket” is a McDonald’s Big Mac, produced in around 120 countries. The Big Mac PPP is the exchange rate that would leave burgers costing the same in America as elsewhere. Thus a Big Mac in China costs 10.5 yuan, against an average price in four American cities of $3.10 (see the first column of the table). To make the two prices equal would require an exchange rate of 3.39 yuan to the dollar, compared with a market rate of 8.03. In other words, the yuan is 58% “undervalued” against the dollar. To put it another way, converted into dollars at market rates the Chinese burger is the cheapest in the table.
经济学人巨无霸指数是建立在一个国际经济学最古老的概念之上的，购买力评价理论。该理论认为，从长期来看，汇率应该调整到等同于不同两个国家相同的一篮子商品和服务价格之比的水平上。而这里的“篮子”就是一个在全世界120个国家都可以买到的麦当劳的巨无霸汉堡。巨无霸购买力是认为汉堡包的在美国和其他地方成本一致。一个巨无霸在中国是10.5元人民币，相反在美国的平均价格是3.10美元（纽约、芝加哥、亚特兰大、旧金山平均价格）。这样算来，1美元等于3.39人民币，而目前的人民币兑美元汇率是8.03，这么说人民币兑美元被低估了58%。并且，在上面的表格中，按市场汇率换算成美元之后，中国的巨无霸汉堡是全世界最便宜的。
In contrast, using the same method, the euro and sterling are overvalued against the dollar, by 22% and 18% respectively; the Swiss and Swedish currencies are even more overvalued. On the other hand, despite its recent climb, the yen appears to be 28% undervalued, with a PPP of only ¥81 to the dollar. Note that all emerging-market currencies also look too cheap.
用同样的方法，欧元和英镑被分别高估了 22%和18% （嗯，对于英镑，我认为是高估了）；而瑞士和瑞典的通货被高估的更多（68%、46%）。（我记得当时在瑞士买了杯麦当劳的咖啡是3瑞郎，约20人民币上下）。 另外，尽管经过了升值，日元仍然被低估了28%. 值得注意的是所有的新兴市场货币看起来都被低估了。
The index was never intended to be a precise predictor of currency movements, simply a take-away guide to whether currencies are at their “correct” long-run level. Curiously, however, burgernomics has an impressive record in predicting exchange rates: currencies that show up as overvalued often tend to weaken in later years. But you must always remember the Big Mac’s limitations. Burgers cannot sensibly be traded across borders and prices are distorted by differences in taxes and the cost of non-tradable inputs, such as rents.
这个指数并不应当被认为是货币汇率变化的准确预测，只是个简易的衡量货币是否在长期均衡水平的指示。不过有意思的是，burgernomics（汉堡包经济学）在预测汇率上还是有惊人的纪录的，所有被认为高估了的货币在几年之内都趋向于走弱。但是也必须明白巨无霸指数的局限。汉堡包不可能被跨国界贸易，价格也被不同的税率，已经诸如房租等不可贸易的成本部分的扭曲了。
Despite our frequent health warnings, some American politicians are fond of citing the Big Mac index rather too freely when it suits their cause—most notably in their demands for a big appreciation of the Chinese currency in order to reduce America’s huge trade deficit. But the cheapness of a Big Mac in China does not really prove that the yuan is being held far below its fair-market value. Purchasing-power parity is a long-run concept. It signals where exchange rates are eventually heading, but it says little about today’s market-equilibrium exchange rate that would make the prices of tradable goods equal. A burger is a product of both traded and non-traded inputs.
尽管有这么频繁的“健康警告”，还是有不少美国政客喜欢过多的引用巨无霸指数，特别是他们需要指责中国的货币和美国巨大的贸易赤字的时候。但是中国汉堡包的廉价并不能证明人民币被压低于它的真正市场价值。购买力平价只是个长期的概念。它只是指示汇率最终的方向，对于当前的使可贸易商品平衡的市场均衡汇率的说明意义并不大。而汉堡包是由可贸易和非可贸易要素组成的商品。
不过，如果有2美元，在美国买不到一个巨无霸汉堡，却能在中国买个巨无霸，然后加上冰淇淋什么的。如果能美国挣钱中国花就好了。 I’m lovin’ it.
另外，有意思的是，虽然经济学人的形式是杂志，但他们自己一直号称是报纸，newspaper。可能因为他们创刊的时候是报纸吧，下面的就是创刊号的照片，已经过了版权保护期了。
