央行的困境：是看透供应冲击还是控制通胀预期？

The Central Bank’sDilemma: Look Through Prepared by Paul Beaudry, Thomas J. Carter and Amartya WP/26/97 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 necessarily 2026MAY IMF Working Paper Monetary and Capital Markets Department The Central Bank’s Dilemma: Look Through Supply Shocks or Control Inflation Expectations? Authorized for distribution by David Hofman 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:When countries are hit by supply shocks, central banks often face the dilemma of either looking through such shocks or reacting to them to ensure that inflation expectations remain anchored. In this paper,we propose a tractable framework to capture this dilemma and explore optimal policy under variousassumptions on how agents form their expectations and the sophistication with which those expectationsaccount for the central bank’s announced policies. While our analysis covers a wide range of potentialspecifications, our baseline results focus on level-k thinking (LKT)–a form of bounded rationality that enjoyssignificant support in the experimental literature and encompasses both adaptive expectations (AE) and Contents 2The environment 3Expectations and optimal policy 3.1.3Level-k thinking (LKT). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .193.2Optimal policy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 4Dynamic policy problem: numerical solution 4.1Generalizing the Phillips curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .324.2Baseline parameterization and solution method. . . . . . . . . . . . . . . . . . . . .33 1Introduction How best to respond to supply shocks is a classic topic in monetary economics, and one that ad-vanced economies’ recent experiences with inflation have brought back to the forefront. Starting in mid-2021, a series of supply shocks led central banks in many countries to ask similar questions:1should they look through supply shocks – even temporarily – at the risk of de-anchoring inflation expectations; or should they immediately tighten monetary policy to keep expectations anchored, this priority against other objectives.2 To adequately address the question of the appropriate policy response to supply shocks, itis important to tackle them in a framework rich enough to capture both the costs and benefitsof looking through these shocks. In our view, this requires two key modelling ingredients: (i) an To preview our model’s main features, the two key ingredients that we just described willrespectively take the form of wage rigidities and a model of bounded rationality that involves level- kthinking but nests both adaptive and rational expectations as special cases.With regard tothe first of these key ingredients, one might be tempted to instead turn to the canonical three-equation New Keynesian (NK) model, which assumes a combination of sticky prices and flexiblewages and plays a central role in many monetary policy discussions. However, as we are reminded shocks).3When facing such shocks, the prescription of the canonical NK model is instead that policy-makers shouldnever look through them, even if they are temporary, since a policy thatadjusts output one-for-one with its natural level will achieve a “divine coincidence” under which the inflation and output gaps are simultaneously closed. As a result, we view the canonical modelas an inadequate laboratory for our analysis but recognize that wage rigidities are well known to To get more specific, we model wage rigidity by considering an economy subject to productivityshocks and assuming that wages are set before observing the current shock, while prices are setafter. This creates potential for wage-price spirals in the sense that wage-setters set wages based However, the cost of looking through supply shocks will be that it could lead to a de-anchoring ininflation expectations, and this brings us to the second of the model’s key ingredients. Here our goalis to understand how outcomes and optimal policy are shaped by the degree of sophistication with which agents form expectations – especially with regard to the way that they account for the central bank’s announced policies in their inflation expectations.To do so, we rely on level-kthinking(LKT), which is a form of bounded rationality that, as we detail below, enjoys significant support With these ingredients in place, we examine how monetary policy should respond to supply shocks when policy-makers aim to minimize a loss function that penalizes deviations of inflationfrom target and employme