统计不应成为政治的奴婢
As he appeals to the British public to vote him in as prime minister, the leader of the opposition proposes collecting new data to provide a better picture of how the country is doing. “Wellbeing can’t be measured by money or traded in markets,” he says. He adds, “We measure all kinds of things but the only thing we don’t measure is the thing that matters most.”
当他呼吁英国公众投票选他当首相时，反对党领导人提议收集新数据，以便更好地了解英国的国情。“福祉无法用金钱衡量，也不能在市场上交易，”他说。他补充说，“我们衡量各种各样的事物，但唯一没有衡量的是那最重要的东西。”
All of the preceding paragraph is true, except for one detail: the first quotation is from David Cameron, then leader of the opposition, in 2006. The second is from Ed Miliband, the current leader of the opposition, a couple of weeks ago. Both men are united, it seems, by a feeling that the most familiar economic measuring stick, GDP (Gross Domestic Product), just isn’t up to the job. Cameron wanted to gather data on wellbeing or happiness; Miliband wants a “cost of living” index. Few reasonable people can object to gathering timely and authoritative economic and social statistics, yet Miliband and Cameron have managed the impressive feat of being cynical and naive at the same time.
上述段落的所有内容都是真实的，只有一个细节例外：第一个引语是2006年戴维•卡梅伦(David Cameron)所说，当时他是反对党领袖。第二个是现任反对党领导人埃德•米利班德(Ed Miliband)几个星期前所讲。两人看起来都有一种相同的感觉：人们最熟悉的经济衡量标尺国民生产总值(GDP)已经不合用。卡梅伦要收集关于福祉或幸福的数据；米利班德想要一个“生活成本”指数。没有多少理性的人反对收集及时、权威的经济和社会统计数据，但米利班德和卡梅伦两人做到了不容易的事，那就是表现得既犬儒又幼稚。The cynical motives in both cases are plain enough — as were, for example, Nicolas Sarkozy’s when, as French president, he commissioned some alternative economic measures that just happened to be more flattering to France. As the leader of a party with a reputation for liking free markets and low taxes, Cameron wanted to soften his image and suggest a broader, more caring perspective. Miliband is trying to replace a government that is presiding over a sudden uptick in GDP, so naturally he wishes to point the spotlight somewhere else.
这两种情况下的犬儒动机是显而易见的——就像尼古拉•萨科齐(Nicolas Sarkozy)还是法国总统的时候那样，他委托出炉了一些另类的经济衡量指标，而这些指标恰好展现法国的长处。作为以崇尚自由市场和低税收出名的保守党的领导人，卡梅伦希望软化自己的形象，暗示一种更包容更关爱的视角。米利班德正试图取代一个成功推动英国GDP突然出现起色的政府，因此，他很自然地想把聚光灯投射到别的地方。
The naivety requires more statistical digging to uncover, and it’s in three parts. The first point is that many of these data already exist. The Office for National Statistics asks questions about wellbeing as part of the Labour Force Survey. The ONS also publishes regular data on inflation, while wage data are in the Annual Survey of Hours and Earnings. Neither Cameron nor Miliband was really asking the statisticians at the ONS to do something new, just to do it more often or in more detail.
揭露幼稚的一面需要挖掘更多统计数据，这需要分为三部分。第一点是，许多此类数据早已存在。英国国家统计局(ONS)在劳动力调查(Labour Force Survey)中问到有关福祉的问题。该局也定期发布通胀数据，而工资数据包含在工时和薪资年度调查(Annual Survey of Hours and Earnings)中。卡梅伦和米利班德并非真的要求国家统计局的统计学家拿出新花样，而只是希望统计的次数更频繁或者内容更加详细。The second point is that no mainstream politician has ever regarded GDP (or its cousin Gross National Product) as the only worthwhile policy objective, although we are often invited to draw that conclusion. Robert Kennedy’s famous complaint that GNP counts “napalm” and “nuclear warheads” but not “the health of our children” or “the strength of our marriages” was wonderful rhetoric — but surely nobody believes that if only the statisticians had collected different data, divorce would be prevented and the Vietnam war would never have happened.
第二点是，从来没有主流政治人物将GDP（或者国民生产总值(GNP)）作为唯一有价值的政策目标，尽管我们经常容易得出这一结论。罗伯特•肯尼迪(Robert Kennedy)曾经说，GNP计入了“凝固汽油弹”和“核弹头”，却没有包括“我们孩子的健康”或者“我们婚姻的力量”；他的这一著名抱怨虽言辞美妙，但谁能相信只要统计学家收集了不同的数据，离婚就可以被阻止，而越南战争就永远不会发生呢？An acerbic comment in Nature last year complained that, “Despite the destruction wrought by the Deepwater Horizon oil spill in 2010 and Hurricane Sandy in 2012, both events boosted US GDP because they stimulated rebuilding.” But this is only a problem if the Deepwater Horizon spill was in some way caused by the collection of GDP data.
去年，《自然》(Nature)杂志上的一个尖刻评论抱怨道：“虽然2010年‘深水地平线’(Deepwater Horizon)石油泄漏和2012年飓风桑迪(Hurricane Sandy)造成了巨大破坏，但这两个事件提振了美国GDP，因为它们刺激了重建工作。”但是，只有在“深水地平线”石油泄漏是GDP数据收集以某种方式所导致的情况下，这才是一个问题。If politicians truly sought to maximise GDP they would immediately abolish all planning restrictions, all barriers to immigration and a good chunk of the welfare state. These ideas are political suicide, which proves that GDP is not the sole objective of public policy — it’s just a way to try to measure the size of the economy.
如果政客们真的试图使GDP最大化，他们就会立即废除所有的市政规划限制、废除所有移民障碍以及福利国家制度的一大部分。这些构想等于政治自杀，这证明了GDP不是公共政策的唯一目标，而只是一种衡量经济规模的方法。The deepest piece of naivety is the idea that — in Ed Miliband’s words — we can measure the one single “thing that matters most”. ONS data on median wages are a case in point. According to one measure, the median wage for people in full-time employment rose just 0.1 per cent in the past tax year — well below the rate of inflation. According to another way of calculating exactly the same number, median wages rose by 4.1 per cent, well above the rate of inflation. (The median is the wage earned by someone slap in the middle of the sample.)
最深层的幼稚是这样的想法：（用米利班德的话说）我们可以衡量一件“最重要的东西”。国家统计局关于中位数工资的数据是一个很好的例子。根据一项衡量指标，全职就业人士的中位数工资在上一个纳税年度仅上涨0.1%，远低于通胀率。而以完全相同数字为依据的另一种计算方法显示，中位数工资增长了4.1%，远高于通胀率。(中位数工资是指样本里处于中间位置者的收入)。How can that be? The lower measure is the median for the entire sample. The higher measure looks at the median wage of people who’ve been in the same job for the entire year — the vast majority. The two numbers would differ if — for example — some high-income people retired and some low-income people joined the labour force (school-leavers? immigrants?). It’s possible for most people to enjoy a decent pay rise while median wages stagnate, and that may be what is happening now. One rather narrow question — “how are things going for people in full-time employment in the middle of the income distribution?” — turns out to have two very different answers. Each one is perfectly justifiable.
怎么会这样呢？较低的测量结果是整个样本的中位数。较高的测量结果针对全年都做同一份工作的人（绝大多数人）的中位数工资。例如，如果一些高收入者退休了，而一些低收入者加入了劳动力大军（中学毕业生？移民？），这两个数字就会有所不同。大多数人享受体面的加薪而中位数工资保持不变的情况是可能发生的，而这可能是现在正在发生的。换句话说，一个相当狭义的问题——“处于收入分配中间位置的全职工作者的境遇如何?”——结果有两个非常不同的答案，而每一个都有无懈可击的依据。We haven’t even got into questions of part-timers, the self-employed, the poorest, the richest, pensioners or benefit recipients. The idea that we can somehow measure “the thing that matters most” is quite absurd.
我们甚至还没有涉及关于兼职者、自由职业者、最贫困人口、最富有的人、养老金领取者或福利领取者的问题。那种认为我们能够以某种方式衡量“最重要的东西”的想法是很荒谬的。It’s the duty of our official statisticians to provide a range of timely and objective statistics that will lead to better decisions. That is why so many different types of data must be gathered, analysed and published. It is a hard job, which is why the ONS has better things to do than help our schoolboy politicians score points off each other.
官方统计学家有责任提供一系列及时客观的统计数据，帮助制定出更好的决策。这就是为什么必须收集、分析并发布如此多不同类型的数据。这是一项艰苦的工作，也是为什么比起帮助幼稚的政客彼此压倒对方，英国国家统计局还有更重要的事情要做。Tim Harford’s latest book, ‘The Undercover Economist Strikes Back’, is now available in paperback. Twitter: @TimHarford
本文作者蒂姆•哈福德(Tim Harford)的新书《卧底经济学家反击战》(The Undercover Economist Strikes Back)的平装本现已上市。Twitter:@TimHarford
