美国制造商抱怨中国低估其汇率。但是是哪项汇率？名义汇率现在是1美元兑6.67元，自9月5日（这一天，贝拉克?奥巴马总统顾问拉里?萨默斯亲自飞到北京抱怨人民币问题）以来上升了近2%，自2005年以来上升了24%。

　　But China’s real exchange rate with America has strengthened by almost 50% since 2005, according to calculations by The Economist (see chart). A real exchange rate takes account of price movements in each country. If prices rise faster in China than in America, China’s real exchange rate goes up, even if its nominal exchange rate stays the same. That’s because higher prices at home make China’s firms less competitive abroad, just as if their currency had gone up.

　　但是根据《经济学人》的计算，自2005年以来，中国与美国的实际汇率上升了近50%。实际汇率把各国的价格波动也考虑在内。如果中国的物价上涨速度比美国快，即便其名义汇率保持不变，中国的实际汇率也会上升。这是因为国内较高的物价是中国公司在国外的竞争力减弱，正如其货币升值一样。

　　To calculate the real exchange rate, you need a gauge of prices in each country. Many economists use the consumer-price index (CPI). But the CPI contains lots of goods and services (such as housing rents) that cannot be traded across borders. Our measure of the real exchange rate, which we will regularly update, offers a more direct measure of competitiveness by looking instead at unit labour costs: the price of labour per widget. These costs go up when wages rise or productivity (widgets per worker) falls. In American manufacturing, unit labour costs have risen by less than 4% since the first quarter of 2005, according to the Bureau of Labour Statistics. In Chinese industry they have risen by 25% over that period, according to our sums.

　　计算实际汇率，你需要每个国家的物价指标。许多经济学家用的是消费价格指数。但是消费价格指数包含了许多无法跨境交易的商品和服务（如住房出租）。我们实际汇率（我们将定期对此进行更新）的衡量标准关注的是单位劳动力成本，更加直接的衡量竞争力：每件产品的劳动力价格。这些价格在工资上涨或生产率（每个工人所生产的产品）下降时就会上涨。根据劳动统计局的数据，自2005年第一季度以来，美国制造业的单位劳动力成本增加不到4%。根据我们的统计，中国工业的单位劳动力成本同期增加了25%。

　　Those estimates are rough and ready. There are no official statistics on China’s unit labour costs. Our calculations are based on the value-added in industry (which extends beyond manufacturing) and the wage bill of urban factories, which does not count the town and village enterprises that employ over two-thirds of China’s metal-bashers. But the urban plants probably churn out a big share of the goodies that America buys.

　　这些都是大致的估算。中国的单位劳动力成本并没有官方统计。我们的估算是基于工业（并不局限于制造业）的增值和城市工厂的工资，这并不包括雇佣逾三分之二中国金属铸造工人的乡镇企业。但是城市工厂可能生产了美国购买的大部分产品。

　　The combination of a 24% rise in the Yuan against the dollar and a 21% increase in Chinese unit labour costs, relative to America’s, explains the steep appreciation shown in the chart. The Yuan may well still be undervalued but our index suggests American manufacturing should have less to fear from Chinese competition than it did five years ago. Until June 2009 appreciation was largely because of the stronger Yuan. Since then it is largely because China’s unit labour costs have grown much faster than America’s. Employers in China’s coastal factories have suffered labour shortages and strikes. America’s factories have reported strong productivity gains as they have wrung more out of the workers that survived the recession (although those gains will be hard to repeat).

　　人民币对美元升值24%和中国的单位劳动力成本相对美国增加21%相结合解释了图表中人民币-美元汇率的大幅升值。人民币币值可能仍然被低估，但是我们的指数表明，与5年前相比，美国的制造商不应该那么担心中国的竞争了。2009年6月前，汇率上升主要是人民币升值造成的。此后，主要是因为中国单位劳动力成本的增长速度比美国快得多。中国沿海工厂的雇主遭受了用工荒和罢工。美国工厂称，由于它们从挺过经济衰退的工人那里获得了更多东西，生产率大幅提高（不过，这样的生产率大幅提高难以再现）。

　　Of course, China and America do not trade only with each other. China’s big surpluses and America’s big deficits depend on the real exchange rate between them and all of their trading partners. But calculating that would require timely estimates of unit labour costs for all of China’s trading partners. That is a bit too laborious.

　　当然，中美并不是只与对方展开贸易。中国的顺差和美国的巨大逆差取决于两国以及它们所有的贸易伙伴之间的实际汇率。但是计算这一实际汇率需要及时地估计所有中国贸易伙伴的劳动力成本。这有点过于费力了。