鑽石舞台

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1.人口統計特徵與自動化

Demographics and Automation

本文從理論和實證上論證得出，老齡化會導致工業自動化程度的提高，原因在於老齡化會造成專門從事手工業生產的中年工人的短缺。本文分析發現，人口結構的變化與各國對機器人等自動化技術的廣泛採用有關，也與美國通勤區（Commuting Zones）內更多的機器人相關活動有關。本文還發現，老齡化進程較快的國家存在更多的自動化創新。據定向技術變革模型預測，在更依賴中年工人的行業和為自動化提供更多技術機會的行業，老齡化的影響會更為明顯；在更容易實現自動化的行業，老齡化會引發生產力的增長和勞動份額的相對下降。

We argue theoretically and document empirically that aging leads to greater (industrial) automation, because it creates a shortage of middle-aged workers specializing in manual production tasks. We show that demographic change is associated with greater adoption of robots and other automation technologies across countries and with more robotics-related activities across U.S. commuting zones. We also document more automation innovation in countries undergoing faster aging. Our directed technological change model predicts that the response of automation technologies to aging should be more pronounced in industries that rely more on middle-aged workers and those that present greater opportunities for automation and that productivity should improve and the labor share should decline relatively in industries that are more amenable to automation. The evidence supports all four of these predictions.

參考文獻：Daron Acemoglu, Pascual Restrepo, Demographics and Automation, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 1–44, https://doi.org/10.1093/restud/rdab031

2. 宏觀經濟學中的收入和財富分配：一種連續時間方法

Income and Wealth Distribution in Macroeconomics: A Continuous-Time Approach

本文重新構建了連續時間下收入和財富分配的Aiyagari-Bewley-Huggett模型。這個主模型，以及更普遍的異質代理人模型，可以被歸結為一個偏微分方程系統。本文主要做出了兩個貢獻。首先，得出了一些新的理論結果：(1) 分析了窮人的消費和儲蓄行為，特別是其邊際消費傾向；(2) 得到了在有兩種收入類型的特殊情況下，財富分配的閉合解；(3) 證明了如果跨期替代彈性小於1，則存在一個特殊的穩態。其次，開發了一種簡單、高效和可移植的算法，該算法可以用於在異質代理人模型中對穩態進行數值求解。

We recast the Aiyagari–Bewley–Huggett model of income and wealth distribution in continuous time. This workhorse model—as well as heterogeneous agent models more generally—then boils down to a system of partial differential equations, a fact we take advantage of to make two types of contributions. First, a number of new theoretical results: (1) an analytic characterization of the consumption and saving behaviour of the poor, particularly their marginal propensities to consume; (2) a closed-form solution for the wealth distribution in a special case with two income types; (3) a proof that there is a unique stationary equilibrium if the intertemporal elasticity of substitution is weakly greater than one. Second, we develop a simple, efficient and portable algorithm for numerically solving for equilibria in a wide class of heterogeneous agent models, including—but not limited to—the Aiyagari–Bewley–Huggett model.

參考文獻：Yves Achdou, Jiequn Han, Jean-Michel Lasry, Pierre-Louis Lions, Benjamin Moll, Income and Wealth Distribution in Macroeconomics: A Continuous-Time Approach, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 45–86, https://doi.org/10.1093/restud/rdab002

3. 了解政府乘數的大小

Understanding the Size of the Government Spending Multiplier: It’s in the Sign

本文認為，財政干預的方向是一個重要但被忽視的決定政府支出乘數的因素。本文通過遞歸識別和敘述性識別兩種方案識別了政府支出衝擊，均得出：與政府支出的負面衝擊相關的收縮性乘數大於1，且在經濟疲軟時最大，而與正向衝擊相關的擴張性乘數總是遠低於1。這些結果有助於理解文獻中看似矛盾的結果。本文還展示了一個具有不完全金融市場和下行名義工資剛性的簡單理論模型如何合理化文章的發現。

This article argues that an important, yet overlooked, determinant of the government spending multiplier is the direction of the fiscal intervention. Regardless of whether we identify government spending shocks from (1) a narrative approach or (2) a timing restriction, we find that the contractionary multiplier—the multiplier associated with a negative shock to government spending—is above 1 and largest in times of economic slack. In contrast, the expansionary multiplier—the multiplier associated with a positive shock—is substantially below 1 regardless of the state of the cycle. These results help understand seemingly conflicting results in the literature. A simple theoretical model with incomplete financial markets and downward nominal wage rigidities can rationalize our findings.

參考文獻：Regis Barnichon, Davide Debortoli, Christian Matthes, Understanding the Size of the Government Spending Multiplier: It’s in the Sign, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 87–117, https://doi.org/10.1093/restud/rdab029

4. 失業保險合同的「菜單」

A Menu of Insurance Contracts for the Unemployed

失業保險（UI）項目在過去主要採用向求職者提供單一保險合同的形式。本文表明，存在逆向選擇和道德風險的情況下，提供一個合同「菜單」可以改善福利。若保險合同由UI保險金和失業時的遣散費組成，提供不同比例的保險金和遣散費的合同，在一個相當於單交叉的條件下是最優的：更需要失業保險的求職者更少出現道德風險問題。此種情形下，「菜單」允許計劃者用有慷慨UI福利的合同吸引對保險有高需求的求職者，而用遣散費豐厚但失業保險很少的合同吸引最容易產生道德風險的求職者。本文還提出了一個簡單的充分統計方法來檢驗數據中的單交叉條件。

Unemployment insurance (UI) programs traditionally take the form of a single insurance contract offered to job seekers. In this work, we show that offering a menu of contracts can be welfare improving in the presence of adverse selection and moral hazard. When insurance contracts are composed of (1) a UI payment and (2) a severance payment paid at the onset of unemployment, offering contracts with different ratios of UI benefits to severance payment is optimal under the equivalent of a single-crossing condition: job seekers in higher need of unemployment insurance should be less prone to moral hazard. In that setting, a menu allows the planner to attract job seekers with a high need for insurance in a contract with generous UI benefits, and to attract job seekers most prone to moral hazard in a separate contract with a large severance payment but little unemployment insurance. We propose a simple sufficient statistics approach to test the single-crossing condition in the data.

參考文獻：Regis Barnichon, Yanos Zylberberg, A Menu of Insurance Contracts for the Unemployed, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 118–141, https://doi.org/10.1093/restud/rdab026

5.作為技術跟隨者的英國：高等教育擴張和大學工資溢價

The U.K. as a Technological Follower: Higher Education Expansion and the College Wage Premium

1993年至2015年間，英國擁有大學學位的人的比例增加了兩倍；與此同時，大學工資溢價的時間趨勢卻異常平緩，學士與碩士的工資差異基本上沒有變化。本文表明，這些模式不能用構成變化來解釋，並本文提出了一個模型以解釋主要模式。在該模型中，企業在集中和分散的組織形式之間進行選擇。本文還表明，該模型具有區別於有外生技能偏向的技術變革模型和內生發明模型的含義，且英國的數據符合這些含義。本文的結果對英國勞動力市場在過去20年中的轉變做出了一致的描述。

The proportion of U.K. people with university degrees tripled between 1993 and 2015. However, over the same period the time trend in the college wage premium has been extraordinarily flat. We show that these patterns cannot be explained by composition changes. Instead, we present a model in which firms choose between centralized and decentralized organizational forms and demonstrate that it can explain the main patterns. We also show the model has implications that differentiate it from both the exogenous skill-biased technological change model and the endogenous invention model, and that U.K. data fit with those implications. The result is a consistent picture of the transformation of the U.K. labour market in the last two decades.

參考文獻：Richard Blundell, David A Green, Wenchao Jin, The U.K. as a Technological Follower: Higher Education Expansion and the College Wage Premium, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 142–180, https://doi.org/10.1093/restud/rdab034

6. 准實驗偏離-份額研究設計

Quasi-Experimental Shift-Share Research Designs

許多研究都使用到了轉移份額工具，即 "Bartik"工具，用暴露份額的權重來平均一組衝擊。本文為轉移份額工具變量（SSIV）回歸提供了一個新的計量經濟學框架，在這個框架中，識別來自於衝擊的准隨機分配，而暴露份額可以是內生的。該框架是由一個等價結果驅動的：轉移份額工具和未觀察到的殘差之間的正交性可以表示為基礎衝擊和衝擊水平的不可觀察性之間的正交性。SSIV的回歸係數同樣可以從等價的衝擊水平的回歸中得到，這就促成了衝擊水平的一致性條件。本文在Autor等（2013）的背景下討論並說明了這個框架的幾個實際見解，估計了中國進口競爭對美國各通勤區製造業就業的影響。

Many studies use shift-share (or 「Bartik」) instruments, which average a set of shocks with exposure share weights. We provide a new econometric framework for shift-share instrumental variable (SSIV) regressions in which identification follows from the quasi-random assignment of shocks, while exposure shares are allowed to be endogenous. The framework is motivated by an equivalence result: the orthogonality between a shift-share instrument and an unobserved residual can be represented as the orthogonality between the underlying shocks and a shock-level unobservable. SSIV regression coefficients can similarly be obtained from an equivalent shock-level regression, motivating shock-level conditions for their consistency. We discuss and illustrate several practical insights of this framework in the setting of Autor et al. (2013), estimating the effect of Chinese import competition on manufacturing employment across U.S. commuting zones.

參考文獻：Kirill Borusyak, Peter Hull, Xavier Jaravel, Quasi-Experimental Shift-Share Research Designs, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 181–213, https://doi.org/10.1093/restud/rdab030

7. 可恢復性和預期驅動的波動

Recoverability and Expectations-Driven Fluctuations

識別結構性經濟擾動的時間序列方法往往要求擾動滿足一些可能與經濟理論不一致的技術條件。本文建議用一個限制性較小的條件，即可恢復性，來取代這些條件。可恢復性只要求擾動可以從可觀察變量中推斷出來。本文展示了可恢復性如何為技術和預期干擾構建新的識別限制。在使用戰後美國數據的向量自回歸例子中，這些限制說明商業周期的一個主要驅動力是對未來技術預期的獨立干擾。

Time series methods for identifying structural economic disturbances often require disturbances to satisfy technical conditions that can be inconsistent with economic theory. We propose replacing these conditions with a less restrictive condition called recoverability, which only requires that the disturbances can be inferred from the observable variables. As an application, we show how shifting attention to recoverability makes it possible to construct new identifying restrictions for technological and expectational disturbances. In a vector autoregressive example using post-war U.S. data, these restrictions imply that independent disturbances to expectations about future technology are a major driver of business cycles.

參考文獻：Ryan Chahrour, Kyle Jurado, Recoverability and Expectations-Driven Fluctuations, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 214–239, https://doi.org/10.1093/restud/rdab010

8. 內生分類的選擇

Choice with Endogenous Categorization

本文提出了分類思維模型（CTM）並對其進行了公理化，在該模型中，決策問題的框架會影響代理人如何對備選方案進行分類，這反過來又會影響他們對問題的評價。顯著性、現狀偏見、損失厭惡、不平等厭惡和當前偏見的模型均適用於CTM。這表明，分類是偏離新古典主義選擇模型的一個根本機制。本文將CTM專門化，為Bordalo等人（2013）提出的突出思維模型提供行為基礎，突出了其強大的預測性和與其他模型的區別。

We propose and axiomatize the categorical thinking model (CTM) in which the framing of the decision problem affects how agents categorize alternatives, that in turn affects their evaluation of it. Prominent models of salience, status quo bias, loss-aversion, inequality aversion, and present bias all fit under the umbrella of CTM. This suggests categorization is an underlying mechanism of key departures from the neoclassical model of choice. We specialize CTM to provide a behavioural foundation for the salient thinking model of Bordalo et al. (2013, Journal of Political Economy, 121, 803–843) that highlights its strong predictions and distinctions from other models.

參考文獻：Andrew Ellis, Yusufcan Masatlioglu, Choice with Endogenous Categorization, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 240–278, https://doi.org/10.1093/restud/rdab011

9. 應該對機器人徵稅嗎？

Should Robots Be Taxed?

本文利用一個以自動化技術進步和內生技能選擇為特徵的定量模型，證明在美國目前的稅收制度下，自動化成本的持續下降會導致收入不平等的加劇。本文描述了該模型中的最佳稅收制度的特徵。本文還發現，在當前幾代不能再轉到非常規職業的上班族活躍在勞動力中時，對機器人徵稅是最理想的；一旦這些工人退休，最佳的機器人稅為零。

Using a quantitative model that features technical progress in automation and endogenous skill choice, we show that, given the current U.S. tax system, a sustained fall in automation costs can lead to a massive rise in income inequality. We characterize the optimal tax system in this model. We find that it is optimal to tax robots while the current generations of routine workers, who can no longer move to non-routine occupations, are active in the labour force. Once these workers retire, optimal robot taxes are zero.

參考文獻：Joao Guerreiro, Sergio Rebelo, Pedro Teles, Should Robots Be Taxed?, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 279–311, https://doi.org/10.1093/restud/rdab019

10. 基於工具與基於目標的規則

Instrument-Based versus Target-Based Rules

本文研究了基於工具與目標的規則。本文的應用是一個新凱恩斯主義的經濟體，在這個經濟體中，中央銀行擁有關於總需求衝擊的非契約性信息，不能對政策作出承諾；通過有社會成本的懲罰激勵中央銀行。基於工具的規則對央行可觀測的政策選擇構成激勵條件；而基於目標的規則對政策結果，如通貨膨脹，構成激勵條件，且這一結果取決於政策選擇和已實現的衝擊。本文表明，每一類規則中的最佳規則都有一個門檻形式，對違規行為施加最嚴重的懲罰。當且僅當中央銀行的信息足夠精確時，基於目標的規則才會優於基於工具的規則，而且中央銀行的承諾問題越不嚴重，基於目標的規則就越有吸引力。只要目標門檻得到滿足，最佳的無約束規則就會放鬆工具門檻。

We study rules based on instruments versus targets. Our application is a New Keynesian economy where the central bank has non-contractible information about aggregate demand shocks and cannot commit to policy. Incentives are provided to the central bank via punishment which is socially costly. Instrument-based rules condition incentives on the central bank’s observable choice of policy, whereas target-based rules condition incentives on the outcomes of policy, such as inflation, which depend on both the policy choice and realized shocks. We show that the optimal rule within each class takes a threshold form, imposing the worst punishment upon violation. Target-based rules dominate instrument-based rules if and only if the central bank’s information is sufficiently precise, and they are relatively more attractive the less severe the central bank’s commitment problem. The optimal unconstrained rule relaxes the instrument threshold whenever the target threshold is satisfied.

參考文獻：Marina Halac, Pierre Yared, Instrument-Based versus Target-Based Rules, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 312–345, https://doi.org/10.1093/restud/rdab027

11. 以個體和團體為基礎的諮詢改善管理：來自哥倫比亞隨機試驗的結果

Improving Management with Individual and Group-Based Consulting: Results from a Randomized Experiment in Colombia

管理質量的差異是造成各國生產力差異的一個重要因素。關於如何最大程度地改善發展中國家的不良管理已成為重要的議題。本文測試了兩種不同的方法來改善哥倫比亞汽車零部件公司的管理。第一種方法為採用密集且昂貴的一對一諮詢，而第二種方法則借鑑了農業推廣方法，為小型企業團體提供諮詢，成本約為前者的三分之一。這兩種方法都帶來了管理實踐的改進，改進幅度相似（8-10個百分點）。以團體為基礎的干預措施導致了企業銷售、利潤和勞動生產率的顯著提高，而對企業績效的影響在幅度上較小，也沒有個體諮詢穩健。這些結果表明，基於團體的方法有可能成為擴大管理改進的途徑。

Differences in management quality are an important contributor to productivity differences across countries. A key question is how to best improve poor management in developing countries. We test two different approaches to improving management in Colombian auto parts firms. The first uses intensive and expensive one-on-one consulting, while the second draws on agricultural extension approaches to provide consulting to small groups of firms at approximately one-third the cost of the individual approach. Both approaches lead to improvements in management practices of a similar magnitude (8–10 percentage points). The group-based intervention leads to significant increases in firm sales, profits, and labour productivity, while the impacts on firm performance are smaller in magnitude and less robust from the individual consulting. The results point to the potential of group-based approaches as a pathway to scaling up management improvements.

參考文獻：Leonardo Iacovone, William Maloney, David McKenzie, Improving Management with Individual and Group-Based Consulting: Results from a Randomized Experiment in Colombia, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 346–371, https://doi.org/10.1093/restud/rdab005

12. 社會連接度與局部蔓延

Social Connectedness and Local Contagion

本文研究了網絡中代理人之間的協調博弈。代理人可以選擇在一個不確定的環境中是否採取行動，同時其鄰居的行動產生的價值越來越大。本文開發了一種算法，將網絡完全劃分為社區，在這些社區中，代理人具有相同的採納傾向。本文的主要發現是，"社會連接度"，一種新的網絡連接度的衡量標準，決定了每個代理人的採納傾向。社會連接度既反映了每個代理人在其社區內的聯繫數量（互連性），也包括了她與其他社區中具有較高採納傾向的成員擁有的聯繫數量(嵌入性)。當且僅當網絡是平衡的，即每個子網絡的平均度數不大於網絡的平均度數時，才存在一個單一的協調集。最後，本文證明，傳染在協調集內是局部的，如對一個代理人的衝擊會統一影響這個代理人和她的協調集的所有成員，但對網絡中的其他代理人沒有影響。

We study a coordination game among agents in a network. The agents choose whether to take action (e.g. adopting a new technology) in an uncertain environment that yields increasing value in the actions of neighbours. We develop an algorithm that fully partitions the network into communities (coordination sets) within which agents have the same propensity to adopt. Our main finding is that a novel measure of network connectedness, which we term 「social connectedness,」 determines the propensity to adopt for each agent. Social connectedness captures both the number of links each agent has within her community (interconnectedness) as well as the number of links she has with members of other communities who have a higher propensity to adopt (embeddedness). There is a single coordination set if and only if the network is balanced—that is, the average degree of each subnetwork is no larger than the average degree of the network. Finally, we demonstrate that contagion is localized within coordination sets, such that a shock to an agent uniformly affects this agent and all members of her coordination set but has no impact on the other agents in the network.

參考文獻：C Matthew Leister, Yves Zenou, Junjie Zhou, Social Connectedness and Local Contagion, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 372–410, https://doi.org/10.1093/restud/rdab022

13. 定向技術變革與工資不平等的基本理論

An Elementary Theory of Directed Technical Change and Wage Inequality

本文將（內生的）定向技術變革理論的核心結果推廣到技術不採取勞動增殖形式和任意多的技能水平的環境中。在簡單的互補性概念的基礎上，這些結果儘管具有一般性，但仍然是直觀的。所開發的理論允許通過定向技術變革理論的視角來研究取代勞動的自動化技術的內生性決定。在一個具有不同技術工人和資本的連續的分配模型中，資本在生產任務中完全替代勞動力，任何技術工人相對供應的增加都會刺激投資於提高資本的生產率，可能會導致技能溢價增加相對技能供應。與此相關的是，與技能稀缺國家的貿易阻礙了資本生產率的提高，可能會逆轉標準的赫克歇爾-奧林效應（Heckscher–Ohlin effects）。

This article generalizes central results from the theory of (endogenously) directed technical change to settings where technology does not take a labour-augmenting form and with arbitrarily many levels of skill. Building on simple notions of complementarity, the results remain intuitive despite their generality. The developed theory allows to study the endogenous determination of labour-replacing, that is, automation technology through the lens of directed technical change theory. In an assignment model with a continuum of differentially skilled workers and capital, where capital perfectly substitutes for labour in the production of tasks, any increase in the relative supply of skilled workers stimulates investment into improving the productivity of capital, potentially leading skill premia to increase in relative skill supply. Relatedly, trade with a skill-scarce country discourages improvements in capital productivity, potentially reversing the standard Heckscher–Ohlin effects.

參考文獻：Jonas Loebbing, An Elementary Theory of Directed Technical Change and Wage Inequality, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 411–451, https://doi.org/10.1093/restud/rdab025

14. 遷徙與非正式保險：來自隨機對照試驗和結構模型的證據

Migration and Informal Insurance: Evidence from a Randomized Controlled Trial and a Structural Model

孟加拉國農村的家庭可以獲得隨機提供的交通補貼，以便在農業歉收季節臨時遷移，這一舉措可以改善其風險分擔。一個關於內生性遷移和風險分擔的理論模型表明，補貼遷移的效果取決於基本的經濟環境。如果遷移是有風險的，臨時補貼可以誘發風險分擔的改善，使遷移有利可圖。本文對該模型進行了估計，發現人口遷移實驗使福利增加了12.9%。反事實分析表明，在同一環境下，移徙成本的永久性而非暫時性的下降會導致風險分擔的減少。

We document that an experimental intervention offering transport subsidies for poor rural households to migrate seasonally in Bangladesh improved risk sharing. A theoretical model of endogenous migration and risk sharing shows that the effect of subsidizing migration depends on the underlying economic environment. If migration is risky, a temporary subsidy can induce an improvement in risk sharing and enable profitable migration. We estimate the model and find that the migration experiment increased welfare by 12.9%. Counterfactual analysis suggests that a permanent, rather than temporary, decline in migration costs in the same environment would result in a reduction in risk sharing.

參考文獻：Costas Meghir, A Mushfiq Mobarak, Corina Mommaerts, Melanie Morten, Migration and Informal Insurance: Evidence from a Randomized Controlled Trial and a Structural Model, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 452–480, https://doi.org/10.1093/restud/rdab021

15. 匯率暴露與企業動態

Exchange Rate Exposure and Firm Dynamics

本文建立了一個異質性的公司動態模型來研究公司的貨幣債務構成和投資選擇。在該模型中，外幣借貸產生於貨幣風險暴露和增長之間的動態權衡。該模型內生地產生了生產性企業的外幣借貸選擇。資本邊際產品高的企業更密集地使用外國貸款。本文利用匈牙利對這些貸款放鬆管制時的企業級普查數據，從經濟角度，評估了模型預測的外匯借款模式，校準了模型，並量化了這種融資的總體影響。反事實檢驗表明，了解公司外幣借款的特徵對於評估這種融資的總體後果至關重要。

This article develops a heterogeneous firm-dynamics model to jointly study firms』 currency debt composition and investment choices. In our model, foreign currency borrowing arises from a dynamic trade-off between exposure to currency risk and growth. The model endogenously generates selection of productive firms into foreign currency borrowing. Among them, firms with high marginal product of capital use foreign loans more intensively. We assess econometrically the model’s predicted pattern of foreign currency borrowing using firm-level census data from the deregulation of these loans in Hungary, calibrate the model, and quantify the aggregate impact of this financing. Our counterfactual exercises show that understanding the characteristics of firms borrowing in foreign currency is critical to assess the aggregate consequences of this financing.

參考文獻：Costas Meghir, A Mushfiq Mobarak, Corina Mommaerts, Melanie Morten, Migration and Informal Insurance: Evidence from a Randomized Controlled Trial and a Structural Model, The Review of Economic Studies, Volume 89, Issue 1, January 2022, Pages 452–480, https://doi.org/10.1093/restud/rdab021