というNBER論文が上がっている（ungated版）。原題は「Strategic Inattention, Inflation Dynamics, and the Non-Neutrality of Money」で、著者はHassan Afrouzi（コロンビア大）。
以下はその要旨。
This paper studies how competition affects firms’ expectations in a new dynamic general equilibrium model with rational inattention and oligopolistic competition where firms acquire information about their competitors’ beliefs. In the model, firms with fewer competitors are less attentive to aggregate variables—a novel prediction supported by survey evidence. A calibrated version of the model matches the relationship between firms’ numbers of competitors and their uncertainty about aggregate inflation as a non-targeted moment. A quantitative exercise reveals that firms’ strategic inattention to aggregates significantly amplifies monetary non-neutrality and shifts output response disproportionately towards less competitive oligopolies by distorting relative prices.
（拙訳）
本稿は、企業が競争相手の考えに関する情報を取得する合理的無関心と寡占的競争を備えた新たな動学的一般均衡モデルにおいて、競争がどのように企業の予想に影響するかを調べた。モデルでは、競争相手が少ない企業ほどマクロ変数に無関心になる*1。これは、サーベイに基づく証拠に支持された新たな予測である。モデルのカリブレートされたバージョンでは、企業の競争相手の数と、マクロのインフレに関する彼らの不確かさの関係を、カリブレーションでマッチ対象としなかったモーメントとしてマッチさせることができた。定量的なモデルの実行結果は、マクロ変数に対する企業の戦略的無関心が貨幣の非中立性を有意に増幅し、相対価格を歪めることにより生産の反応を競争の少ない寡占企業に偏らせることを明らかにした*2。
論文の冒頭では研究の背景について以下のように説明している。
Almost every modern monetary model relates price changes to firms’ expectations about aggregate inflation. However, recent literature documents that firms’ inflation expectations are inaccurate and disconnected from aggregate inflation (Candia, Coibion, and Gorodnichenko, 2021). Furthermore, the accuracy of firms’ expectations about aggregate variables correlates with the number of their competitors (Coibion, Gorodnichenko, and Kumar, 2018). These facts are inconsistent with our standard models and raise two questions: (1) How does competition affect firms’ expectations? (2) What are the macroeconomic implications of the interaction between competition and expectation formation?
（拙訳）
現代の金融モデルはほぼ全て、価格の変化を、マクロのインフレについての企業の予想と関連付けている*3。しかし、最近の研究は、企業のインフレ予想が不正確であり、マクロのインフレとは断絶していることを明らかにした（Candia, Coibion, and Gorodnichenko, 2021*4）*5。また、マクロ変数についての企業の予想の正確さは、競争相手の数と相関する（Coibion, Gorodnichenko, and Kumar, 2018*6。）。これらの事実は、我々の標準的なモデルと矛盾しており、2つの疑問を惹起する。(1) 競争はどのように企業の予想に影響するのか？ (2) 競争と予想形成の相互作用がマクロ経済にとって持つ意味は何か？
*1:結論部では「Oligopolistic firms find it optimal to acquire more information and pay direct attention to the beliefs of their competitors, an incentive that is stronger when they have fewer competitors or higher strategic complementarities in pricing. ...Moreover, in tracking their competitors’ beliefs, firms ignore aggregate shocks, and, as a result, their beliefs about aggregate variables are more inaccurate and noisy than the beliefs that feed into their prices. Thus, firms’ expectations about aggregate variables are no longer the appropriate measures for their decisions with oligopolies.」と記述されている。
*2:結論部では「The model’s implications for monetary non-neutrality and inflation dynamics speak to recently documented trends in rising concentration and market power. These results suggest that with more concentration, monetary policy is more potent and its real effects are stronger. Furthermore, the reallocative effects of strategic inattention imply that this change in potency is not uniform across all firms. These heterogeneous effects introduce new distortions to relative prices that might lead to new sources of misallocation and, more broadly, to efficiency loss, which should be of interest for future research.」と記述されている。
*3:原注（リンクは小生が付与）：With sticky prices, inflation increases with expected future inflation (Woodford, 2003b). In models of information rigidity, it increases with past expectations of current inflation (Lucas, 1972, Mankiw and Reis, 2002, Reis, 2006).
*4:Do You Know that I Know that You Know…? Higher-Order Beliefs in Survey Data* | The Quarterly Journal of Economics | Oxford Academic、cf. 貴兄が知っていることを私が知っていると貴兄は知っているのか？ サーベイデータにおける高次の考え - himaginary’s diary。
*5:原注（リンクは小生が付与）：See, also, Kumar, Afrouzi, Coibion, and Gorodnichenko (2015).
*6:How Do Firms Form Their Expectations? New Survey Evidence - American Economic Association。
