数字货币交易所刘焕军(北京交易所将成立数字货币交易中心)

　　一些美国人口普查数字认为，过去几十年来美国平均家庭收入增长十分缓慢。那么，美国中产阶级收入真的在停滞吗？

　　提高中产阶级家庭收入的挑战已成为美国总统选战的重要焦点。所有人都同意，得益于高科技教育和股价攀升带来的巨大收益，顶层人群的收入几十年来可谓狂飙突进。

　　改进帮助那些陷入贫穷之人的计划——如食品券和基于经济调查的退休金——也得到了总体支持。但公共争论的重点集中在如何帮助数量更加庞大(在政治上也更加重要)的中产阶级。

　　在这方面，改进现有政府计划可以带来很大的助益：扩大贴近市场的培训、增加已婚妇女加入或回归劳动力大军的机会、降低社会保障规则中对继续聘用年长工人的惩罚条款、改变税收规则以提高生产率和工资等。

　　但是，尽管加强这些计划应该作为重点，但也不能忽视中产阶级家庭在过去几十年中的实际表现。不幸的是，政治争论被误导性的统计数字所扭曲，这些数字从总体上低估了中产阶级家庭的得益。

　　比如，人们常说，过去几十年来平均家庭收入增长十分缓慢(甚至停滞不前)。一些美国人口普查数字似乎支持这一结论。但更准确的政府数据表明，位于收入分布中端的家庭的实际收入自1980年以来增加了大约50%。如果针对生活成本进行更合适的调整，那么中产阶级的收益还会大大提高。

　　美国人口普查局测算家庭所有来源的总货币收入，并确定区别收入分布前50%和后50%的分界线。这就是中位家庭收入。为了比较不同时间的中位家庭收入，当局将这些年收入的美元价值除以消费物价指数，得到实际中位家庭收入。这样获得的数字表明，从1984年到2013年的收入累计增长还不到10%，相当于每年增长不到0.3%。

　　任何在此期间内生活在美国的成年人都会认识到，这个数字总体低估了普通家庭的收益。表明这一数字存在问题的一个指标是政府还估算非农商业部门雇员实际时薪从1985年到2015年提高了39%。

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　　官方人口普查测算存在三个重要问题。首先，它没有认识到人口组成的改变；今天的家庭与30年前的家庭区别很大。此外，人口普查局的收入测算口径过窄，中产阶级家庭不但收到越来越多的政府转移支付，也从所得税率的降低中获益。最后，人口普查局所使用的物价指数没有体现新产品和产品改进对美国生活水平提高的重要贡献。

　　先来看家庭组成的变化。从1980年到2010年，由单身男女组成的“家庭”比例从26%增加到33%，而包括成婚夫妇的家庭比例从60%下降到50%。

　　无党派的国会预算办公室(CBO)在进行1979—2011年间家庭收入变化的详细研究时，将收入的定义进行了扩展，食品券等非现金福利和医疗等实物福利也被计算在内。该研究还扣除了联邦税，而联邦税占中产阶级家庭税前收入的比例1980年为19%，2010年降至11.5%。为了将年收入换算为实际收入，CBO使用了消费支出物价平减指数，许多人认为，在换算实际收入中，该指标优于消费物价指数。CBO还单独进行了经家庭规模调整的分析。

　　从传统货币收入定义出发，CBO发现实际中位家庭收入在1980—2010年间仅仅增加了15%，与人口普查局的测算相当。但若把收入的定义扩大，将减税的收益包括进来时，CBO发现中位家庭实际收入增加了45%。经家庭规模调整的分析将这一收益进一步提高到53%。

　　而即使是这一大大提高了的增幅，也可能大大低估了实际生活水平的提高。在有关部门的测算中，美元收入通过一个反映现有商品和服务价格变化的物价指数换算为实际收入指标。但这一物价指数没有反映新产品或已有商品和服务的改进。

　　因此，如果所有人的货币收入较一年前增加了2%，而所有商品和服务的价格也上涨了2%，则官方测算将表明实际收入没有变化，即使新产品和重要质量改进增加了我们的福利。事实上，美国政府根本没有将谷歌[微博]和Facebook等互联网服务所创造的价值计算在内，因为这些服务没有被购买。

　　没人知道这些产品创新和改进给我们增加了多少福利。但假设这些收益只相当于每年1%，过去三十年累计下来也能造成35%的增长。将这个数字与CBO所测算的50%左右的收益相加，意味着实际中位家庭收入在过去30年的年增长率接近2.5%。

　　因此美国中产阶级的表现比统计悲观派所认为的要好得多。而如果有更好的政策，这些家庭未来还会做得更好。

　　【原文】

　　Are USMiddle-Class Incomes Really Stagnating?

　　By Martin Feldstein

　　CAMBRIDGE – The challenge of raising theincomes of middle-class families has emerged as an important focus of thepresidential election campaign in the United States. Everyone agrees thatincomes at the top have surged ahead in recent decades, helped by soaring rewardsfor those with a high-tech education and rising share prices. And there isgeneral support for improving programs – such as food stamps and means-testedretiree benefits – that help those who would otherwise be poor. But the publicdebate is largely about how to help the more numerous (and politically moreimportant) middle class。

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　　Here, much can be done by improvingexisting government programs: expanding market-relevant training, increasingopportunities for married women to join or rejoin the labor force, reducing thepenalties in Social Security rules for continued employment by older workers,and changing tax rules in ways that will increase productivity and wages。

　　But, while strengthening such programs should be a high priority, weshould not lose sight of how well middle-income families have actually doneover the past few decades. Unfortunately, the political debate is distorted bymisleading statistics that grossly understate these gains。

　　For example, it is frequently said that theaverage household income has risen only slightly, or not at all, for the pastfew decades. Some US Census figures seem to support that conclusion. But moreaccurate government statistics imply that the real incomes of those at themiddle of the income distribution have increased about 50% since 1980. And amore appropriate adjustment for changes in the cost of living implies asubstantially greater gain。

　　The US Census Bureau estimates the money incomETHat households receive from all sources and identifies the income level thatdivides the top and bottom halves of the distribution. This is the median householdincome. To compare median household incomes over time, the authorities dividethese annual dollar values by the consumer price index to create annual realmedian household incomes. The resulting numbers imply that the cumulative increasefrom 1984 through 2013 was less than 10%， equivalent to less than 0.3% per year。

　　Any adult who was alive in the US duringthese three decades realizes that this number grossly understates the gains ofthe typical household. One indication that something is wrong with this figureis that the government also estimates that real hourly compensation ofemployees in the non-farm business sector rose 39% from 1985 to 2015.

　　The official Census estimate suffers fromthree important problems. For starters, it fails to recognize the changingcomposition of the population; the household of today is quite different fromthe household of 30 years ago. Moreover, the Census Bureau’s estimate of incomeis too narrow, given that middle-income families have received increasing governmenttransfers while benefiting from lower income-tax rates. Finally, the priceindex used by the Census Bureau fails to capture the important contributions ofnew products and product improvements to Americans’ standard of living。

　　Consider first the changing nature ofhouseholds. From 1980 to 2010, the share of “households” that consisted of justa single man or woman rose from 26% to 33%， while the share that containedmarried couples declined from 60% to 50%。

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　　When the nonpartisan Congressional BudgetOffice (CBO) conducted a detailed study of changesin household incomes from 1979 to 2011, it expanded the definition of income toinclude near-cash benefits like food stamps and in-kind benefits like healthcare. It also subtracted federal taxes, which fell from 19% of pretax incomefor middle-income households in 1980 to just 11.5% in 2010. To convert annualincomes to real incomes, the CBO used the price deflator for consumerexpenditures, which many believe is better for this purpose than the consumerprice index. The CBO also presented a separate analysis that adjusted forhousehold size。

　　With the traditional definition of moneyincome, the CBO found that real median household income rose by just 15% from1980 to 2010, similar to the Census Bureau’s estimate. But when they expandedthe definition of income to include benefits and subtracted taxes, they foundthat the median household’s real income rose by 45%. Adjusting for household sizeboosted this gain to 53%。

　　And, again, even this more substantial riseprobably represents a substantial underestimate of the increase in the realstandard of living. The authorities arrive at their estimates by converting dollarincomes into a measure of real income by using a price index that reflects thechanges in the prices of existing goods and services. But that price index doesnot reflect new products or improvements to existing goods and services。

　　Thus, if everyone’s money incomes rose by 2%from one year to the next, while the prices of all goods and services also roseby 2%， the official calculation would show no change in real incomes, even ifnew products and important quality improvements contributed to our wellbeing. Indeed,the US government does not count the value created by Internet services likeGoogle and Facebook as income at all, because these services are not purchased。

　　No one knows how much such productinnovations and improvements have added to our wellbeing. But if the gains havebeen worth just 1% a year, over the past 30 years that would cumulate to a gainof 35%. And combining that with the CBO estimate of a gain of about 50% wouldimply that the real income of the median household is up nearly 2.5% a year overthe past 30 years。

　　So the US middle class has been doing muchbetter than the statistical pessimists assert. And with better policies, thesehouseholds can do even better in the future。

　　本文作者介绍：马丁?费尔德斯坦(MartinFeldstein)，哈佛大学经济学教授，国家经济研究局主席，1982—1984年任罗纳德?里根总统经济顾问委员会主席。

　　责任编辑：NONO Han

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