But how strong is the anchor? There are at least three types of inflation expectations: those priced into financial markets; those that appear in surveys of households and businesses; and those of professional forecasters. Market expectations have been spooking hawks. The ten-year bond yield has risen to about 1.7%, up from 0.5% in early August. However, the inflation expectations incorporated in these yields remain broadly consistent with the Fed's target. The bigger problem is tail risk. William Marshall of Goldman Sachs, a bank, calculates that the implied inflation risk premium—in effect, the price of insuring against very high inflation—has risen. The market-implied probability of average consumer-price inflation exceeding 3% per year for the next five years is over 30%, according to the Minneapolis Fed. That does not imply 1970s-style inflation, but would be uncomfortable for the Fed.
但这个锚有多强固呢？至少存在三类通胀预期: 反映在金融市场定价上的预期；在对家庭和企业的调查中表现出的预期；以及专业预测机构的预期。市场预期一直让鹰派紧张。十年期债券收益率已从去年8月初的0.5％升至约1.7％。但是，这个收益率水平中已隐含的通胀预期仍然与美联储的目标大体上一致。更大的问题是尾部风险。高盛的威廉马歇尔（William Marshall）计算得出，隐含的通胀风险溢价（也就是对抗极高通胀的价格）已经上升。根据明尼阿波利斯联储的数据，市场隐含的未来五年平均消费者物价通胀每年在3％以上的概率超过30％。这并非意味着会出现70年代那样的通胀，但会让美联储不安。
The evidence suggests that survey expectations are more important than market prices. Households' inflation expectations have not budged much, though consumers, like investors, have become less certain about the future. The danger is that the public is poorly informed, and its expectations are therefore fickle. Even firms do not seem to pay much attention to inflation nowadays. When Olivier Coibion of the University of Texas and three co-authors surveyed top executives in April 2018, 55% said that they did not know what inflation would be over the next year. When they do have a view, both firms and households chronically overestimate price rises. Consumers seem unduly swayed by the price of petrol. The authors concluded that the public's expectations looked "anything but anchored".
有证据表明，调查中表现的预期比市场价格更为重要。尽管消费者和投资者一样对未来的不确定性有所提高，但家庭的通胀预期并没有太大变化。危险在于公众掌握的信息匮乏，因此他们的预期也会变幻无常。如今即使是企业似乎也不太重视通胀。得克萨斯大学的奥利维尔科比恩（Olivier Coibion）和三位报告合著者在2018年4月调查了企业高层管理人员，结果有55％的人表示他们不知道明年的通胀会是多少。当他们有一定的判断时，企业和家庭都会习惯性地高估价格上涨的程度。消费者的预期受油价的影响似乎过大。这几位作者得出的结论是，公众的期望看起来“完全没有锚定”
Professional forecasters can give Mr Powell most comfort. They are nearly unanimous and unwavering in believing what the Fed says about the long term. Yet their historical record as an early warning signal is not encouraging. As the economy overheated in the late 1960s prognosticators were behind the curve, according to the Livingston survey, the best available record of their views.
可以给鲍威尔最多安慰的是专业预测机构。它们几乎完全一致并且毫不动摇地相信美联储对长期的看法。然而，这些机构在提前预警方面的历史表现并不鼓舞人心。利文斯顿专业预测调查（Livingston Survey）是迄今可得的对这些机构预测的最翔实记录，它显示在上世纪60年代后期经济过热时，它们的预警就滞后了。
Part of the explanation is that forecasting inflation is hard. Even with today's vastly improved methods, after two years the consensus inflation forecast is on average off by 0.4 percentage points in one direction or another, calculates Goldman Sachs. Someone who forecasts that a central bank's target will lose credibility before it happens can look unhinged. Even Mr Summers—who does not suffer from excessive humility—couches his predictions in probabilities which make it nearly impossible for him to be proved wrong.
部分原因是通胀很难预测。即使今天所采用的方法已大为改进，但据高盛估算，对两年后通胀的预测共识平均而言仍偏高或偏低0.4个百分点。预测央行的目标会失去可信度的人可能会让人觉得满嘴呓语。就连萨默斯这样绝非谦虚过头的人也会用概率来表达他的预测，让人日后几乎没法说他是错的。
Joseph Gagnon of the Peterson Institute, a think-tank, says the Fed should promise "dramatically" higher interest rates if inflation rises and does not fall back. Saying this too soon would knock confidence. Arguably, however, the Fed is undermining the implicit understanding that it will tackle overheating by emphasising its duty to ensure a thriving jobs market that reduces inequality. That makes it harder to imagine the central bank crushing inflation by engineering a recession, as happened in the 1980s. Should enough people doubt its hypothetical resolve, the door to persistently higherinflation—or to a painful credibility test—would be ajar.
智库彼得森研究所（Peterson Institute）的约瑟夫加农（Joseph Gagnon）表示，美联储应承诺若通胀上升后不回落就会“大幅”加息。过早这样表态会打击信心。然而，美联储强调它有职责确保就业市场繁荣以减少不平等，这也可说是在动摇市场默认它会解决经济过热问题。这让人更难想象美联储会像上世纪80年代那样，通过制造衰退来抑制通胀。如果有足够多的人怀疑美联储意愿的坚定，那就将推开一扇大门，它通向通胀的持续上升——或一次痛苦的可信度测试。
