不完全信息、需求冲击的构成和菲利普斯曲线的平坦化

Imperfect Information,Composition of DemandShocks, and the Flatteningof the Phillips Curve Tatsushi Okuda, Tomohiro Tsuruga, and Francesco Zanetti WP/26/57 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. 2026MAR IMF Working Paper Monetary and Capital Markets Department Imperfect Information, Composition of Demand Shocks, and the Flattening of the Phillips CurvePrepared by Tatsushi Okuda, Tomohiro Tsuruga, and Francesco Zanetti* Authorized for distribution by Mahvash QureshiMarch 2026 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:We study why inflation responds differently to economic activity over time. Using survey datacovering the universe of Japanese firms, we show that firms are unable to perfectly distinguish aggregate fromsector-specific demand changes, leading to positively correlated expectations about these two components.We develop a model with imperfect information that reproduces this pattern and predicts that higher relativevolatility of sector-specific demand reduces the sensitivity of inflation to changes in aggregate demand, thusflattening the Phillips curve. Testing this prediction with Japanese data from 1976 to 2022, we find thatincreases in the volatility of sectoral demand shocks explain significant changes in the Phillips curve slope overthe sample period. Our results provide a novel explanation for the flattening of the Phillips curve: thecomposition of shocks -- not just their magnitude -- critically affects the sensitivity of inflation to aggregatedemand. RECOMMENDED CITATION:Okuda, Tatsushi, Tomohiro Tsuruga, and Francesco Zanetti (2026) “ImperfectInformation, Composition of Demand Shocks, and the Flattening of the Phillips Curve” IMF Working PaperWP/26/57, International Monetary Fund, Washington DC. * The authors would like to thank Jesus Fernandez-Villaverde, Gaetano Gaballo, Laura Gati, Nobuhiro Kiyotaki, Jennifer La’O,Xiaowen Lei, Alistair Macaulay, Sushanta Mallick, Sophocles Mavroeidis, Taisuke Nakata, Shigenori Shiratsuka, Chris Sims,Wataru Tamura, Takayuki Tsuruga, Laura Veldkamp, Mirko Wiederholt, Xiaowen Wang, Yifan Zhang, and seminar participants atthe University of Oxford, SWET 2018, 2018 JEA Autumn Meeting, WEAI 2019, Inflation: Drivers and Dynamics Conference 2019,Econometric Society European Winter Meeting 2020, Econometric Society North American Summer Meeting 2021, workshop onNew Directions in Inflation Forecasting, Royal Economic Society 2022 Annual Conference, and the ECB-Cleveland FedConference 2022 for extremely valuable comments and suggestions. The views expressed in this paper are those of the authorsand do not necessarily represent the views of the Bank of Japan, IMF, its Executive Board, or IMF management. Imperfect Information,Composition of Demand Shocks,and the Flattening of the PhillipsCurve Prepared by Tatsushi Okuda, Tomohiro Tsuruga, and Francesco Zanetti1 1Introduction A large class of macroeconomic models builds on the premise that firms set prices to maximizeprofits by optimally responding to demand, and several studies show that shocks to demandare heterogeneous and reflect aggregate and sector-specific disturbances.1The classic studyby Ball and Mankiw (1995) shows that the optimal price changes if the movement in demandoriginates from the aggregate shock, but it remains unchanged if the movement originatesfrom the sector-specific shock. In reality, however, information is imperfect and firms cannotperfectly distinguish the source of changes in demand. Thus, firms optimally adjust pricesbased on expectations about whether the source of the demand change stems from aggregateor sector-specific disturbances. Despite the centrality of expectations to price changes, empirical evidence on expectationsabout the distinct aggregate and sector-specific components of demand is scarce. Moreover,despite a tight link between the source of the shock and the firm’s optimal pricing decisionoften assumed in standard models with perfect information, there are no studies that connectimperfect information on the different components of demand to the sensitivity of inflationto economic activity. Our analysis fills these gaps by providing novel empirical evidence on the formation ofexpectations about the different components of demand from unique sector-level survey datafor the universe of Japanese firms, and developing a simple model of imperfect informationthat links those expectations to the sensitivity of inflation to economic activity.We showthat imperfect informatio