It would be an understatement to say that economic forecasts are a constant disappointment to investors. The trouble arises because the forecasters’ models are fundamentally flawed.
如果有人说，经济预测反复令投资者失望，这将是一种客气的说法。之所以出现这个问题，是因为预测者的模型存在根本瑕疵。
Many are over-reliant on extrapolations of the recent past, while the so-called New Keynesian models deployed by professional economists rarely pick up big economic shifts, such as the 1970s oil shock or the rapid rise of China.
许多模型过于依赖外推法（基于不久前的过去推断未来），同时专业经济学家运用的所谓“新凯恩斯”模型很少注意到重大的经济转变，比如上世纪70年代的石油冲击或者中国的快速崛起。
Such shifts are inherently unpredictable. Yet there are some fundamental regime changes that ought to be predictable and which forecasters may now be overlooking. The most obvious, which will be hugely important for capital markets, relates to demography and the impending shrinkage of the global workforce.
此类转变从本质上说是不可预测的。然而，有一些理应可以预料到的根本性机制变化，现在可能被预测者们忽视了。对资本市场至关重要的最明显的改变，与人口特征和即将出现的全球劳动人口缩减有关。
The experience of the past 35 years has been one of labour oversupply arising from the postwar baby boom in the advanced economies and the incorporation of the emerging markets into the global economy. This has put downward pressure on wages. At the same time, excessive global saving, notably in Asia and northern Europe, has helped cause low or negative real interest rates.
过去35年是劳动力供应过剩的35年，这一方面源于发达经济体战后的“婴儿潮”，另一方面源于新兴市场融入全球经济。这让薪资承受下行压力。与此同时，全球（尤其是在亚洲和北欧）储蓄过剩，催生了较低或为负值的实际利率。
Today the baby boomers are retiring, and there is nothing remotely comparable in the pipeline to the addition of China to the global trading system. And China itself is ageing rapidly at a relatively early stage in its development. So a negative labour shock is looming, which coincides with declining fertility. That is a recipe for a shift from disinflation back to inflation.
如今，“婴儿潮一代人”即将退休，而且像当年中国加入全球贸易体系那样的重大事件在可预见的未来不会再有。中国本身正在“未富先老”——还处于发展的相对早期阶段，老龄化却很快。因此负面的劳动力冲击即将来临，此时恰逢生育率下降。在这种情况下，通胀放缓会恢复为通胀。
Ah, you say, but inflation is always and everywhere a monetary phenomenon, so the logic is surely flawed. Well, maybe. But in a paper for the Bank for International Settlements, the central bank for central banks, Mikael Juselius and El?d Takáts found a very strong link between trend inflation and the age structure of the population in 22 advanced economies between 1955 and 2014. The larger the proportion of young and old in the total population, the higher the inflation.
哦，你会说，但通胀在任何时候、任何地点都是一种货币现象，因此上述推断肯定有问题。或许如此吧。但在央行的央行——国际清算银行(Bank for International Settlements)发表的一份研究报告中，米卡埃尔?尤塞柳斯(Mikael Juselius)和埃卢德?陶卡奇(El?d Takáts)发现，从1955年至2014年期间，22个发达经济体的趋势通胀水平与人口的年龄结构存在非常密切的关联。总人口中非劳动人口所占比例越高，通胀就越高。
These effects were large enough to explain most trend inflation during the period. In the US, the baby boomers increased inflation by an estimated six percentage points between 1955 and 1975 and lowered it by five percentage points between 1975 and 1990, when they entered working life. Across the 22 countries in the sample, the age-structure effect explained about five percentage points of the reduction in the average rate of inflation from the late 1970s to the early 2000s.
这些影响已显著到能够解释上述期间的大部分趋势通胀水平。在美国，“婴儿潮一代人”据估计在1955年至1975年期间让通胀提升了6个百分点，在他们进入劳动年龄的1975年至1990年期间让通胀降低了5个百分点。在作为样本的22个国家里，年龄结构影响解释了从上世纪70年代末到本世纪头几年，平均通胀率降幅中的约5个百分点。
Why central banks failed to respond appropriately is moot. What does seem likely in the light of the data is that economists and central bankers have exaggerated the role of expectations in forming inflation.
谈论各国央行为何未能正确回应已经没有意义。从该数据看，经济学家和央行行长们似乎的确夸大了预期在塑造通胀中的角色。
Given that we know, barring catastrophes, how many people will enter the labour market in 20 years’ time because they have already been born, it ought to be possible to forecast inflation on this basis. Mr Juselius and Mr Takáts have done that, reckoning that inflation will be about three percentage points higher on average in 40 years from 2016, due to ageing.
鉴于我们知道有多少人将会在20年内进入劳动力市场（除非发生灾难），因为他们已经出生，那么在这个基础上预测通胀应该是可行的。尤塞柳斯和陶卡奇就这样做了，他们估算出，从2016年起的40年，通胀率平均将因老龄化上升约3个百分点。
That, of course, leaves out the delicate question of timing. If the shift comes sooner rather than later, today’s bond market would see a nasty bust. It is also worth asking what could go wrong with such a forecast.
当然，这没有考虑到微妙的时机问题。如果转变出现得更早、而非更晚，如今的债券市场将会出现严重危机。还有必要问的是，此类预测可能在哪里出错。
If baby boomers work longer than their parents, the picture could be very different. Yet so far people in the developed world are extending working lives very slowly. Robotics could provide competition for humans in the labour market, reducing the bargaining power of labour. I believe this scare story is overdone, though that is a story for another day.
如果“婴儿潮一代人”的工作年限比上一辈长，局面可能截然不同。然而迄今为止，发达世界中的人们延长工作年限非常缓慢。机器人可能在劳动力市场构成人类的竞争对手，削弱劳方讨价还价的能力。我认为这种可怕故事有些夸张，不过那是另一回事了。

More importantly, the record of forecasting on the basis of demography has not been impressive. Many in the 1980s forecast less-buoyant housing markets in the US and UK on the basis of a declining proportion of young people in the population. They were spectacularly wrong. The conventional wisdom in Japan in the 1980s was that ageing would be inflationary, which is not how it has worked so far.
更重要的是，基于人口特征的预测一直以来都不是很准。在上世纪80年代，许多人基于幼年人口占比下降，预测美国和英国住房市场将不太活跃。他们错得离谱。日本在上世纪80年代的普遍观点是，老龄化将会导致通胀，迄今以来的情况并非如此。
For my money, the best case for suggesting a return to inflation is not demographics but debt. It is hard to see how the rise in developed-world public sector debt to astonishingly high levels since the financial crisis can be managed without informal default through inflation. A demographically induced rise in the general price level would provide a very convenient palliative for over-indebted governments.
在我看来，最能预示通胀回归的因素不是人口特征，而是债务。发达世界自金融危机以来累积的巨额公共部门债务，如果不以通胀方式非正式违约，那么很难想象这些债务如何能收得了场。人口特征导致的普遍价格上涨，将恰逢其时地为过度负债的政府帮一个大忙。