# ミクロ経済ショックのマクロ経済への影響：ハルテンの定理を超えて

デロングがEquitable Growthブログで表題の論文をShould-Readとして紹介している（H/T Economist's View）。原題は「Macroeconomic Impact of Microeconomic Shocks: Beyond Hulten’s Theorem」で、著者はDavid Rezza Baqaee（LSE）、Emmanuel Farhi（ハーバード大）。デロングがリンクしたのは12/26付けのWPだが、昨年の2月にはNBERにも上がっている（そちらは6月に改訂されている）。

We provide a nonlinear characterization of the macroeconomic impact of microeconomic productivity shocks in terms of reduced-form non-parametric elasticities for efficient economies. We also show how structural parameters are mapped to these reduced-form elasticities. In this sense, we extend the foundational theorem of Hulten (1978) beyond first-order terms. Key features ignored by first-order approximations that play a crucial role are: structural elasticities of substitution, network linkages, structural returns to scale, and the extent of factor reallocation. Higher-order terms magnify negative shocks and attenuate positive shocks, resulting in an output distribution that is asymmetric, fat-tailed, and has a lower mean even when shocks are symmetric and thin-tailed. In our calibration, output losses due to business-cycle fluctuations are an order of magnitude larger than the cost calculated by Lucas (1987). Second-order terms also show how shocks to critical sectors can have large macroeconomic impacts, tripling the estimated impact of the 1970s oil price shocks.
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