In the spring of 2020 American consumer prices fell for three consecutive months as the pandemic struck. Rents collapsed, hotel rooms went empty and oil prices turned negative. All sudden spurts of deflation or inflation make the news twice: first when they happen and then a year later, when they distort comparisons that look back 12 months. Sure enough on April 13th statisticians announced that consumer prices in March were fully 2.6% higher than a year earlier, up from 1.7% in February. The increase in headline inflation was the biggest since November 2009, when similar "base effects" were in play after the global financial crisis.
2020年春天大流行爆发后，美国的消费者价格指数连续三个月下降。租金暴跌，酒店客房空空如也，油价下跌。所有突然爆发的通货紧缩或通货膨胀都会出现两次新闻：首先是当它们发生的时候，然后是一年后，当他们对过去12个月进行歪曲对比时。果然，4月13日，统计人员宣布三月份的消费者价格指数比去年同期上涨了2.6%，高于二月份的1.7%。这是自2009年11月以来的最大增幅，当时全球金融危机后也出现了类似的“基数效应”。
It would be wrong, however, to dismiss the rise in inflation as a mere mathematical quirk. America's economy is emerging from the downturn at great speed as jobs return and vaccinated consumers start spending. In March alone prices rose by 0.6% compared with the previous month, the fastest pace since 2012. Much of that was driven by a big increase in petrol prices but even the "core" consumer-price index (CPI), which strips out food and energy prices, was up by 0.3% (an annualised pace of 4.1%). Services prices in particular have started to rebound: hotel rooms were 4.4% dearer than a month earlier and rent, a big component of the index, has firmed in recent months. Capital Economics, a consultancy, predicts that the combination of base effects and a boomy reopening will drive the headline annual rate of inflation close to 4% by May.
然而，如果认为通胀上升只是数学上的怪癖，那就大错特错了。随着就业机会的恢复和消费者开始消费，美国经济正以极快的速度从衰退中复苏。仅3月份，房价就比上月上涨了0.6%，这是自2012年以来的最快涨幅。这主要是由于汽油价格的大幅上涨，但即使是剔除食品和能源价格的“核心”消费者价格指数(CPI)也上涨了0.3%(折合成年率为4.1%)。特别是服务价格已经开始反弹：酒店客房价格比一个月前上涨了4.4%，而作为该指数重要组成部分的租金在最近几个月也趋于稳定。咨询公司凯投宏观预测，基数效应和繁荣的重新开业将推动5月份的年通货膨胀率接近4%。
The Federal Reserve targets annual inflation of 2%, but on a different measure— the price index for personal consumption expenditures—which tends to run about a third of a percentage point cooler than CPI. Still, if prices rise at a monthly pace consistent with the Fed's target, as they roughly have in recent months, base effects mean that the target will soon be exceeded in annual terms. Any heat in the economy will lead to further overshooting.
美联储的年通胀率目标是2%，但采用的是另一种衡量标准——个人消费支出的价格指数——它往往比CPI低约三分之一。然而，如果物价以与美联储目标一致的月度速度上涨，就像近几个月来的情况一样，基数效应意味着每年的目标将很快被超越。经济中的任何过热都将导致进一步的过热。
The path of inflation matters more than usual because of the amount of economic uncertainty in the air. The relaxation of social-distancing restrictions, President Joe Biden's enormous $1.9trn economic stimulus and the unusual doveishness of the Fed, which is employing a new monetarypolicy framework, together comprise an inflation experiment. It has turned some doves into hawks, with economists such as Larry Summers, a former treasury secretary, and Olivier Blanchard, a former chief economist of the IMF, warning of the risk of overheating. And, as the administration follows up its stimulus with an infrastructure bill, how the experiment pans out will help determine how much more deficit spending the economy can take.
由于空气中弥漫着大量的经济不确定性，通胀的走势比以往更为重要。放松社交距离限制、美国总统乔·拜登推出1.9万亿美元的巨额经济刺激计划，以及美联储非同寻常的鸽派态度(美联储正在采用新的货币政策框架)，共同构成了一项通胀实验。它已经把一些鸽派变成了鹰派，前财政部长拉里·萨默斯和前国际货币基金组织首席经济学家奥利维尔·布兰查德等经济学家警告了经济过热的风险。而且，随着奥巴马政府在刺激计划之后推出一项基础设施法案，这项试验的结果将有助于决定美国经济还能承受多大的赤字支出。
