导读：
1月5日，英格兰银行首席经济学家安迪·霍尔丹在英国智库政府研究所的发言中表示，经济预测已经陷入困境。他说，经济学家对2008年金融危机的预测失败堪比迈克尔·菲什播报1987年飓风时的失误。迈克尔·菲什曾任BBC气象播阅读全文
1月5日，英格兰银行首席经济学家安迪·霍尔丹在英国智库政府研究所的发言中表示，经济预测已经陷入困境。他说，经济学家对2008年金融危机的预测失败堪比迈克尔·菲什播报1987年飓风时的失误。迈克尔·菲什曾任BBC气象播报员，在他声称英国不会遭遇飓风的第二天，也就是10月19日星期一，飓风就席卷了英国，整个伦敦陷入瘫痪。
去年六月英国脱欧公投之前，经济学家预测，脱欧一旦成真，2016年下半年的英国经济将大幅下滑。然而，英国经济活力依旧，或许是预测与现实之间存在一个时间差。尽管经济学家做预测时凭的是电脑屏幕和芯片数据，不是水晶球和残剩茶叶，但是，差错还是明摆着。
国际货币基金组织对它的一系列预测和委任工作进行了事后的反思和独立的研究。结论表示，对2008年金融危机的失测，部分应归咎于群体性思维——国际货币基金组织的预测很少偏离大多数的意见。独树一帜成为众矢之的的情况很罕见。一个人犯错不可饶恕，一群人犯错则情有可原。这种情况在国别办事处设立之后变得更为严重，各级政府对背离众道的预测颇有微词。群体主义最显著地表现在来自新兴市场经济数据(EMED)的高度一致的预测上——在来自40位预测者的结论中，对于2017年增长率和通胀率预测的标准差为0.3%；对于中国通胀率的预测算是例外，标准差有0.5%。
预测家凭借的都是一样的数据和短期模型。这些模型大多以凯恩斯乘数论和投资加速论为基础，设定数据变动会遵循以往的规律。不考虑政策因素，之前上升的会继续上升，之前下降的会继续下降，不存在拐点。金融市场的动荡是已知的未知。
当经济越来越偏离先前一致的标准差时，预测的错误最为明显。EMED收集了39份关于美国的预测，其中33份来自于银行和金融机构，只有6份来自独立的预测方。很少有预测方背后是使用设定模型的大型团队。大部分预测方是小型经济学家团队，所得结论与经济合作与发展组织、国际货币基金组织、欧盟和其他官方预测相差无几。金融机构当然不愿意预言危机引起慌乱。
展望2017年，上月EMED对九个主要经济体的平均预测结果显示，除美国和加拿大外，增长率全部下调，此外，预计通胀会在所有经济体中加快到来。预测结果会高度一致，主要是由于对预测的修正频次不够，很少有预测者每月调整他们的预测。一致的预测距离现实往往慢半拍，有些还是老掉牙的。
口径一致的经济学家们现在又忙着为2017年的增长和通胀做乐观的评估。没有谁会预测市场动荡。债券利率急速上升带来的风险在快增长和快通胀的情况下显得尤为突出。如果保守主义政策和报复性政策占据主导的话，寄望于唐纳德·特朗普所承诺的亲商计划的人们可能要失其所望。预测中上升的还会升得更高，但之后就会跌得更快。
这一切在2017年可能不会发生，但这仅是短期的乐观。转折点已经可以预期，这或许又意味着另一场金融危机。在众多潜在威胁中，我们还不知道最终点燃导火索的会是来自何处的冲击。且让我们重温英国诗人罗伯特·赫里克的名句：
玫瑰当摘需及早，
时光飞逝不复还：
此朝满目花含笑，
明晨花落香自消。
英文原文：
Speaking to the Institute for Government on 5 January, Andy Haldane, chief economist at the Bank of England, admitted that economic forecasting was in crisis. He called the failure to predict the 2008 financial crisis a ‘Michael Fish’ moment, referring to the 1987 instance when BBC weather forecaster Michael Fish famously declared that a hurricane would not hit Britain. It hit the next day, Monday 19 October, and closed the City.
Before the UK-EU referendum in June of last year, economists predicted a sharp downturn in the second half of 2016 following a vote for Brexit. Instead, the economy remained buoyant, possibly a timing error. Computer screens and silicon chips have replaced crystal balls and tea leaves, but something is clearly wrong with economic forecasting.
The International Monetary Fund conducts post-mortems on its forecasts and commissions independent studies. These suggest that its failure to predict the 2008 financial crisis was partly due to group-think – IMF forecasts rarely depart far from the consensus. There is an unwillingness to stand out from the crowd and be subject to scrutiny. Being alone and wrong is a sin. Being together and wrong is excused. This is aggravated by the inputs of state department country desks, and governments chastise forecasters for adverse predictions. Groupism is on display especially in consensus forecasts from Emerging Markets Economic Data – among nearly 40 forecasters, standard deviation for 2017 growth and inflation are 0.3%. Chinese inflation is the exception, with a 0.5% deviation.
Forecasters rely on the same data and short-term models. Largely based upon Keynesian multipliers and investment accelerators, these models suppose the data will continue to follow the same path as before. Policy apart, what went up goes up, what went down goes down, and turning points don’t exist. Financial shocks are known unknowns.
But forecasting errors are most pronounced when economies turn to a greater degree than the consensus standard deviation. EMED collects 39 forecasts for the US, of which 33 are from banks and financial institutions and only six from independent forecasters. Few have large teams using bespoke models. Many are small economist teams expressing no more than marginal disagreements with the Organisation for Economic Co-operation and Development, IMF, European Union or official forecasts. Financial institutions are of course reluctant to predict crises and spread alarm.
Looking to 2017, last month’s EMED average forecasts for nine major economies predicted slower growth for all except the US and Canada and faster inflation across the board. High frequency consensus forecasts are based on lower frequency forecast revisions, and few forecasters fine tune their predictions every month. Consensus forecasts are lagging and some are already stale.
The consensus is now busy writing-up 2017 growth and inflation. Few may predict market turmoil. The danger of a more abrupt rise in bond rates is clear in the light of faster growth and inflation. Euphoria around Donald Trump’s proposed and supposedly business-friendly plans may subside if protectionist policies and retaliation take the centre stage. Forecasts which go up go up faster, and then come down faster.
This may prove unlikely in 2017, and short-term optimism need not be misplaced. Thereafter, however, a turning point is predictable, including possibly another financial crisis. We do not know what shock, among numerous potential threats, might trigger it. To quote the English poet Robert Herrick: ‘Gather ye rosebuds while ye may, Old Time is still a-flying; And this same flower that smiles today, tomorrow will be dying.’