美国通货膨胀的兴衰：最新进展

The Rise and Retreat ofUS Inflation: An Update Laurence Ball, Daniel Leigh and Prachi Mishra WP/25/94 IMF Working Papersdescribe research inprogress by the author(s) and are published toelicit comments and to encourage debate.The views expressed in IMF Working Papers arethose of the author(s) and do not necessarilyrepresent the views of the IMF, its Executive Board,or IMF management. 2025MAY IMF Working Paper The Western Hemisphere Department The Rise and Retreat of US Inflation: An UpdatePrepared byLaurence Ball, Daniel Leigh andPrachi Mishra* Authorized for distribution byNigel ChalkMay2025 IMF Working Papersdescribe research in progress by the author(s) and are published to elicitcomments and to encourage debate.The views expressed in IMF Working Papers are those of theauthor(s) and do not necessarily represent the views of the IMF, its Executive Board, or IMF management. ABSTRACT:Why did US inflation rise over 2021-22 and why has it retreated since then? Ball, Leigh, andMishra (2022), writing near the inflation peak, explained the rise with a framework in which inflation depends onthree factors: long-term expectations; the tightness of the labor market as measured by the vacancy-to-unemployment (V/U) ratio; and large changes in relative prices in particular industries such as energy andautos. This paper finds that the same framework explains the retreat in inflation since our earlier work. I.Introduction After a quarter century of quiescence, US inflation rose sharply during the COVID-19 pandemic. The twelve-month CPI inflation rate rose from an average of 2.1 percent over 2017-2019 to 9.0 in June 2022, alarmingeconomists and the public. Then inflation started declining and in March 2025 it stood at 2.4, most of the wayback to its pre-pandemic level. A large body of research has studied that experience. One contribution to this literature is our earlier work: Ball, Leigh, and Mishra (2022). That paper analyzed datathrough September 2022, when inflation was near its peak, and sought to explain why inflation had risensharply. We offered an explanation based on three factors: the tight labor market over 2021-2022, as capturedby an extremely high ratio of job vacancies to unemployment (V/U); sharp rises in relative prices in certainindustries, such as energy and autos; and a modest rise in long-term inflation expectations. This paper asks whether the factors that explain the rise in inflation can also explain the fall since late 2022.We conclude that they can. All three drivers of the inflation increase have reversed: the tightness of the labormarket has diminished; pricesin sectors such as energy and autos have fallen; and long-term inflationexpectations have returned to pre-pandemic levels. As a result, the inflation equations estimated in our earlierpaper, which fit the data through September 2022, also fit the subsequent fall in inflation. Section 2 of this paper reviews the behavior of CPI inflation since 2020. As in our earlier work, we decomposethe headline inflation rate into two components: core inflation, as measured by the weighted median inflationrate from the Federal Reserve Bankof Cleveland; and “headline shocks” arising from large relative-pricechanges in particular industries. We see that the inflation surge over 2021-2022 reflected both rising coreinflation and positive headline shocks, and both declining core and negative shocks have contributed to thesubsequent disinflation. Section 3 informally examines the drivers of inflation since 2020, and Section 4 estimates the equation for core(weighted median) inflation from our 2022 paper. We estimate the equation for the earlier paper's sampleperiod of 1985 through September 2022, and with the sample extended through March 2025. We find that fittedvalues from our estimated equation follow actual core inflation fairly closely over the entire period from 2020through 2025—even when the equation is estimated with the shorter sample,in which case the fitted valuesafter September 2022 are out-of-sample conditional forecasts. As of March 2025, the actual level of twelve-month core inflation is 3.5 and the fitted values are 3.1 and 3.2 for the shorter and extended samples,respectively. Section 5 examines the sources of headline-inflation shocks, which in our framework affect inflation bothdirectly and by passing through into core inflation. We again estimate an equation from our 2022 paper, onethat explains headline shocks with changesin the relative prices of energy and autos and a measure of supplychain disruptions. We find that movements in these variables explain most of the positive headline shockswhen inflation was rising and most of the negative shocks when inflation was falling. Finally, Section 6 summarizes our interpretation of the post-COVID inflation experience. The rise in twelve-month inflation from January 2020 to the peak in June 2022 is explained primarily by positive headline shocks,which raised inflation both direct