The Big Mac index

英国《经济学家》杂志编制的一个不是很严谨的指数。 该杂志比较麦当劳巨无霸汉堡包(Bid Mac)在世界各地的价格，作为各国币值是否被低估或高估的指南。其假设是相似的食品无论在哪里销售，其价格应当是相同的，价格有差别意味着币值出现异常 情况。例如，一个巨无霸汉堡包在华盛顿的价格为1美元，而在鲁利坦尼亚(Ruritania，假想国)为20比索，那幺，美元兑比索应是1美元等于20比 索。如果汇率偏离这一水平，根据购买力平价理论，比索的币值要幺偏低，要幺偏高。购买力平价理论认为，汇率应变动至令相同的商品组合价格一致的水平。批评者认为，巨无霸汉堡包指数忽略了不同国家的税收、利润水平和原材料价格等因素的影响。
根据数据 在今年2月份的时候在美国大概需要3.22美元购买一个巨无霸， 同期 在中国我们需要花上11元人民币 购买同样的巨无霸。 同期美元对人民币汇率 1：7.77 ， 这意味着在中国我们花上1.41美元就可以购买到一个巨无霸！！根据这个数据 得出来的结论 人民币 相对美元 的实际价值 有 56％的折价。 虽然这个数据不是一个严谨的指数，不过却是从一个侧面告诉我们我国的物价其实还是比较便宜的，相对于我们的人民币汇率来说！

The Big Mac index

Feb 1st 2007
From Economist.com

The Economist's Big Mac index is based on the theory of purchasing-power parity (PPP), according to which exchange rates should adjust to equalise the price of a basket of goods and services around the world. Our basket is a burger: a McDonald’s Big Mac.

The table below shows by how much, in Big Mac PPP terms, selected currencies were over- or undervalued at the end of January. Broadly, the pattern is such as it was last spring, the previous time this table was compiled (see article). The most overvalued currency is the Icelandic krona: the exchange rate that would equalise the price of an Icelandic Big Mac with an American one is 158 kronur to the dollar; the actual rate is 68.4, making the krona 131% too dear. The most undervalued currency is the Chinese yuan, at 56% below its PPP rate; several other Asian currencies also appear to be 40-50% undervalued.

The index is supposed to give a guide to the direction in which currencies should, in theory, head in the long run. It is only a rough guide, because its price reflects non-tradable elements—such as rent and labour. For that reason, it is probably least rough when comparing countries at roughly the same stage of development. Perhaps the most telling numbers in this table are therefore those for the Japanese yen, which is 28% undervalued against the dollar, and the euro, which is 19% overvalued. Hence European finance ministers’ beef with the low level of the yen.