The outlook for China's housing sector is both crucially important for the world economy and─because of weakness in the data─very hard to predict.

　　中国房地产行业的前景对世界经济有着至关重要的意义，但又非常难以预测，原因就出在数据的薄弱。

　　Despite a government push this year for more-accurate home-price data from China's National Bureau of Statistics, international markets─and most Chinese consumers─remain deeply dubious of the official monthly figures.

　　虽然政府今年努力提高国家统计局房价数据的准确性，但国际市场和中国国内大多数消费者对于这个官方月度数据仍然存在深深的怀疑。

　　July data from the National Bureau of Statistics are due out Thursday, but confidence in the official figures is so low that the markets pay more attention to numbers from a private data provider, the China Real Estate Index System.

　　按计划，国家统计局周四将公布7月份数据，但市场对官方数据很不相信，所以把更多注意力放在了民间数据提供者“中国房地产指数系统”提供的数据上面。

　　China, an engine of global growth, has to do better at explaining this key sector of its economy. Take Shanghai, the country's financial hub and richest city. According to data from the China Real Estate Index System, prices of new apartments in Shanghai have risen by more than 150% in the past five years. That outpaces a 107% increase in wages over the same period─moving home ownership further out of reach for average earners.

　　作为全球经济增长引擎的中国需要更好地阐释自身经济中的这个关键行业。以全国金融中心、最富裕城市上海为例。中国房地产指数系统显示，上海新房价格在过去五年里上涨150%以上。这超过同期107%的工资涨幅，使买房对于收入一般的人变得更加遥不可及。

　　But the official data tell a different story. According to China's NBS, prices for new apartments in Shanghai have climbed 20% over the past five years─well below the increase in wages.

　　但官方数据反映的是另一种情况。国家统计局数据显示，过去五年上海新房价格上涨20%，远低于工资涨幅。

　　As important, though the trend in both data series is upward, the path mapped out by the private data is more volatile─with bigger ups and downs in the growth rate than in the official data.

　　同样重要的是，虽然两组数据的趋势都是上涨，但民间数据描述的轨迹波动性更大，涨幅的扩大、收缩幅度都大于官方数据。

　　Why is the difference between those two sets of figures so important? (Full disclosure: I investigate the question in detail in my book 'Understanding China's Economic Indicators.') Investment in residential real estate accounts directly for 12% of China's gross domestic product, and more than that when demand for steel, cement, and other construction materials is factored in. China's real-estate boom helps energize the domestic economy and keeps miners from Australia to Brazil flush with cash.

　　为什么说两组数据的差别如此重要呢？（备注：我在自己的《理解中国经济指标》(Understanding China's Economic Indicators)一书中详细探讨了这个问题。）住宅类房地产投资直接占到中国国内生产总值(GDP)的12%，如果把钢铁、水泥和其他建筑材料的需求考虑在内，这个比例还会更大。中国楼市的繁荣振兴了国内经济，也让澳大利亚、巴西等国的矿商赚得盆满钵满。

　　House prices are a key leading indicator of changes in policy, sales and investment. Rising prices attract speculators into the market. Entrepreneurs and billionaires descend on Beijing and Shanghai with suitcases of cash, snapping up entire floors of luxury residential developments. Higher sales encourage developers to break ground on more-lavish projects. But if prices rise too fast, the government has to step in to cool the market, speculators move to the sidelines, and developers put down their tools.

　　Reuters周日，一名工人为合肥一座大楼安装窗户。房价是政策、销售和投资变化的重要先行指标。房价上涨吸引炒客入市。企业家和亿万富豪提着一箱箱的钞票奔赴北京和上海，整层整层地抢购豪华住宅开发项目。销售增长鼓励开发商开建更加奢华的项目。但如果房价上涨过快，政府就得出手冷却市场，炒客就得退到一边，开发商就得偃旗息鼓。

　　Beijing could be forgiven for a little tardiness in getting up to speed on housing data. The boom that has made developers and speculators rich and left young professionals grasping for the first rung on the real-estate ladder is a recent phenomenon. As recently as 15 years ago, the private property market was almost nonexistent. Home for most workers was employer-provided housing. But with an incipient property bubble threatening to cause economic disorder and social unrest, the government has attempted to bring prices under control, with the latest crackdown kicking off in April 2010.

　　中国政府在了解房地产数据方面略有迟缓或许情有可原。楼市繁荣造富开发商和炒客、让年轻职业人士争先恐后进入房地产市场，是最近才有的一个现象；15年前，私人房地产市场还基本不存在，多数劳动者的住房都是单位提供的。但由于初现端倪的房地产泡沫可能造成经济混乱和社会动荡，政府一直希望把房价控制下来，最新一轮调控在2010年4月份展开。

　　Of course, if prices have risen only as fast as the official data suggest, there is no need to worry. With just a slight mismatch between prices and incomes, a brief period with a slower increase in prices will improve affordability. When that happens, the government will be able to loosen its controls, sales will rise, and developers will be powering up their cement mixers─reassuring international markets that the economy is humming along. If the official numbers are also correct that house prices typically move gradually and within a small range, even continued controls by the government are unlikely to result in a sharp correction.

　　当然，如果房价上涨的速度仅仅是与官方数据显示的一样，那就没有必要担忧。如果房价和收入之间仅有小幅的不匹配，那么短暂的房价上涨速度放慢就能提高居民置业的负担能力。如果是这样的情况，政府将能够放松管制，房屋销量将会上升，开发商将让水泥搅拌机开始运转，而这些现象能让国际市场相信中国经济充满活力。如果现实情况也有如官方数据所显示的那样，即房价通常只是逐渐上涨，且幅度较小，那么即便政府继续控制房价也不可能导致楼市的大幅回调。

　　But if─as seems more likely─the China Real Estate Index System data are correct and prices are considerably out of whack with income, the government in Beijing and reluctant local officials will have to maintain controls on the sector for a long time, raising the specter of a rough patch for China's economy. Equally worrying, if movements in prices are as volatile as the private data suggest, the chances of a policy misstep leading to a sharp correction are higher.

　　但如果中国房地产指数系统的数据是正确的，房价涨幅远远高于工资涨幅（看上去现实更可能是这种情况），那么中央政府和不情愿的地方官员将不得不长时间维持对地产业的控制，这会提高中国经济陷入困境的风险。同样令人担心的是，如果房价变动的幅度正如中国房地产指数系统显示的那样剧烈，那么政策失误导致剧烈回调的可能性会更高。

　　Despite, or perhaps because of, the importance attached to real estate, there are few areas of China's economy where the official data are less reliable. In 2009, the combination of a slowdown in growth that hit many home buyers in the pocketbook and continued failure by statisticians to report the rapid increase in house prices evident to would-be buyers was too much for public opinion to bear.

　　尽管中国房地产业非常重要（或者也可能正因为其重要性），中国经济中却没有几个行业的官方数据比地产业更不可靠。2009年，经济增速放缓令许多购房者荷包受损，而统计人员则多次未能公布快速上涨的房价（在潜在购房者看来，这再明显不过），这两个因素叠加在一起令公众舆论难以接受。

　　The National Bureau of Statistics’ announcement of an increase in average house prices of just 1.5% was met with public skepticism. One Chinese Internet commentator asked: ”Can you believe that? Obviously a misplaced decimal point.“

　　国家统计局公布的房屋均价涨幅仅为1.5%，遭到公众的质疑。中国一位网络评论员问道：你相信这个数字吗？小数点显然放错位置了。

　　Outrage over the 2009 data sparked some change. But the new system rolled out in January wasn't much of an improvement. On the plus side, outdated and unrepresentative samples that analysts believe were to blame for problems with the old data were replaced by a system that captures every sale of new property. On the down side, the national average figure─the best guide to the overall state of China's housing sector and a major focus of market attention─was shelved in favor of more detailed city-level data. That differs from practices in the U.S., where the monthly Standard & Poor's Case-Shiller index and new-home sales data from the Census Bureau both provide national benchmarks for price changes as well as city or regional breakdowns.

　　公众对2009年数据的愤怒引发了一些变化。但今年1月推出的新系统的改进并不大。从有利的一面看，过时且不具代表性的样本被一个能捕捉每一个新房销售数据的系统所替代。分析师认为，上述过时且不具代表性的样本正是导致与老数据有关的各种问题的原因。从不利的一面看，全国平均数据不再发布，取而代之的是更为详细的市级数据。全国平均数据被认为是观测中国住房市场整体状况的最佳指南，也是市场关注的主要焦点。中国的这种做法和美国不同。在美国，标准普尔公司（Standard & Poor's）发布的Case-Shiller月度房价指数以及人口普查局（Census Bureau）发布的新房销售数据均会提供房价变动的全国基准值，并做城市或区域分解。

　　Adding to the confusion, local officials in China control the flow of high- and low-price property on to the market, affecting the movement of the data. Nicole Wong, China property analyst at CLSA, said when the government cracks down on property speculators, officials withhold permission for developers to bring high-value properties to market─contributing to the appearance of falling prices. When the heat is off, more-expensive developments are allowed back in.

　　此外，中国地方官员控制进入市场的高价房和低价房的数量也让相关数据更令人困惑。地方官员此举会影响数据的变动。里昂证券（CLSA）中国地产业分析师王艳（Nicole Wong）说，当政府打击楼市投机现象时，地方官员就不许开发商向市场推出高价房，这会造成房价下跌的假象。当风头过去以后，更多高价房又被允许进入市场。

　　Sleight of hand by local officials─moving the house-price index without changing the underlying situation─does little to solve China's housing bubble, or to provide investors and policy makers with an accurate understanding of the sector. If the Chinese government is serious about controlling runaway house prices, the first step should be to provide credible data on exactly how high home prices actually are.

　　没有改变根本情况，只是改变了房价指数──地方官员玩的这种小把戏对解决中国的楼市泡沫问题没有帮助，也无法让投资者和决策者准确了解中国房地产业的状况。如果中国政府是在严肃对待控制失控房价的问题，那么要走的第一步应该是准确提供房价到底有多高的可靠数据。