1. Empirical Strategies in Economics: Illuminating the Path From Cause to Effect

經濟學中的實證策略:厘清從原因到結果的路徑

Joshua D. Angrist

Abstract?：The view that empirical strategies in economics should be transparent and credible now goes almost without saying.

經濟學中的經驗策略應該是透明和可信的，這種觀點現(xiàn)在幾乎不用再強調了。

By revealing for whom particular instrumental variables (IV) estimates are valid, the local average treatment effects (LATE) framework helped make this so.

通過揭示特定的工具變量(IV)估計對誰有效，局部平均處理效應的(LATE)框架有助于實現(xiàn)這一點。

This lecture uses empirical examples, mostly involving effects of charter and exam school attendance, to illustrate the value of the LATE framework for causal inference.

本講座使用實證案例（主要涉及特許學校考試出勤率的影響）來說明因果推斷的LATE框架的價值。

LATE distinguishes independence conditions satisfied by random assignment from more controversial exclusion restrictions.

LATE將隨機分配應滿足的獨立條件與更有爭議的排除限制區(qū)別開來。

A surprising exclusion restriction is shown to explain why enrollment at Chicago exam schools reduces student achievement.

一個令人驚訝的排除限制被證明可以解釋為什么芝加哥考試學校的入學考試會降低學生的成績。

I also make two broader points: IV exclusion restrictions formalize commitment to clear and consistent explanations of reduced-form causal effects; the credibility revolution in applied econometrics owes at least as much to compelling empirical analyses as to methodological insights.

我還提出兩個更廣泛的觀點:工具變量排除限制正式承諾對簡化形式因果關系的清晰和一致解釋；應用計量經濟學的可信性革命至少要歸功于令人信服的實證分析，而不是方法論上的洞見。

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2 Causality in Econometrics: Choice vs Chance

計量經濟學中的因果關系：選擇與機會

Guido W. Imbens

Abstract?：This essay describes the evolution and recent convergence of two methodological approaches to causal inference.

這篇文章描述了兩種因果推斷方法的演變和最近的趨同。

The first one, in statistics, started with the analysis and design of randomized experiments.

第一種，在統(tǒng)計學中，從隨機實驗的分析和設計開始。

The second, in econometrics, focused on settings with economic agents making optimal choices.

第二種，在計量經濟學中，關注經濟主體做出最佳選擇的環(huán)境。

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I argue that the local average treatment effects framework facilitated the recent convergence by making key assumptions transparent and intelligible to scholars in many fields.

我認為，局部平均治療效果框架通過使許多領域的學者能夠透明和理解關鍵假設，促進了最近的趨同。

Looking ahead, I discuss recent developments in causal inference that combine the same transparency and relevance.

展望未來，我將討論因果推斷的最新發(fā)展，這些發(fā)展結合了相同的透明度和相關性。

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3 Robust Empirical Bayes Confidence Intervals

穩(wěn)健的經驗貝葉斯置信區(qū)間

Timothy B. Armstrong, Michal Kolesár, Mikkel Plagborg-M?ller

Abstract：?We construct robust empirical Bayes confidence intervals (EBCIs) in a normal means problem.

我們在正態(tài)均值問題中構建了穩(wěn)健的經驗貝葉斯置信區(qū)間（EBCI）。

The intervals are centered at the usual linear empirical Bayes estimator, but use a critical value accounting for shrinkage.

置信區(qū)間通常以線性經驗貝葉斯估計器為中心，但使用考慮收縮的臨界值。

Parametric EBCIs that assume a normal distribution for the means (Morris (1983b)) may substantially undercover when this assumption is violated.

假設均值呈正態(tài)分布的參數(shù)EBCI（Morris （1983b））在違反此假設時可能會大量隱藏。

In contrast, our EBCIs control coverage regardless of the means distribution, while remaining close in length to the parametric EBCIs when the means are indeed Gaussian.

相比之下，無論均值分布如何，我們的EBCI都控制覆蓋范圍，同時當均值確實是高斯時，其長度與參數(shù)EBCI保持接近。

If the means are treated as fixed, our EBCIs have an average coverage guarantee: the coverage probability is at least 1???α on average across the n EBCIs for each of the means. ?

如果均值被視為固定值，則我們的EBCI具有平均覆蓋保證：每個均值的n個EBCI的覆蓋概率平均至少為1 ? α。

Our empirical application considers the effects of U.S. neighborhoods on intergenerational mobility.

我們的實證應用考慮了美國社區(qū)對代際流動性的影響。

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4.General Equilibrium Effects of Cash Transfers: Experimental Evidence From Kenya

現(xiàn)金轉移支付的一般均衡效應——來自肯尼亞的實驗證據(jù)

Dennis Egger, Johannes Haushofer, Edward Miguel, Paul Niehaus, Michael Walker

Abstract?：How large economic stimuli generate individual and aggregate responses is a central question in economics, but has not been studied experimentally.

大規(guī)模的經濟刺激如何產生個體和總體反應是經濟學的核心問題，但尚未進行實驗研究。We provided one-time cash transfers of about USD 1000 to over 10,500 poor households across 653 randomized villages in rural Kenya.

我們向肯尼亞農村653個隨機村莊的10500多個貧困家庭提供了約1000美元的一次性現(xiàn)金轉移支付。

The implied fiscal shock was over 15 percent of local GDP.

隱含的財政沖擊超過當?shù)谿DP的15%。

We find large impacts on consumption and assets for recipients.

我們發(fā)現(xiàn)對接受者的消費和資產有很大的影響。

Importantly, we document large positive spillovers on non-recipient households and firms, and minimal price inflation.

重要的是，我們記錄了對非受援家庭和企業(yè)的巨大正溢出效應，以及最低的價格通脹。

We estimate a local transfer multiplier of 2.5. We interpret welfare implications through the lens of a simple household optimization framework.

我們估計本地轉移乘數(shù)為2.5。我們通過簡單的家庭優(yōu)化框架來解釋福利影響。

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5.Uneven Growth: Automation's Impact on Income and Wealth Inequality

增長不平衡：自動化對收入和財富不平等的影響

Benjamin Moll, Lukasz Rachel, Pascual Restrepo

Abstract?：The benefits of new technologies accrue not only to high‐skilled labor but also to owners of capital in the form of higher capital incomes. This increases inequality. To make this argument, we develop a tractable theory that links technology to the distribution of income and wealth—and not just that of wages—and use it to study the distributional effects of automation. We isolate a new theoretical mechanism: automation increases inequality by raising returns to wealth. The flip side of such return movements is that automation can lead to stagnant wages and, therefore, stagnant incomes at the bottom of the distribution. We use a multiasset model extension to confront differing empirical trends in returns to productive and safe assets and show that the relevant return measures have increased over time. Automation can account for part of the observed trends in income and wealth inequality.

摘要：新技術的好處不僅惠及高技能勞動力，也惠及資本所有者，其資本收入較高。這加劇了不平等。為了證明這一論點，我們開發(fā)了一種易于處理的理論模型，將技術與收入和財富的分配聯(lián)系起來，而不僅僅是工資的分配，并用它來研究自動化的分配效應。我們分離出一種新的理論機制：自動化通過提高財富回報來增加不平等。這種回報路徑的另一面是，自動化可能導致工資停滯不前，從而導致分配底部的收入停滯不前。我們使用多資產模型擴展來面對生產性和安全資產回報的不同經驗趨勢，并表明相關的回報措施隨著時間的推移而增加。自動化可以解釋觀察到的收入和財富不平等趨勢的一部分。

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6.Multinationals, Monopsony, and Local Development: Evidence From the United Fruit Company

跨國公司、壟斷和地方發(fā)展：來自聯(lián)合水果公司的證據(jù)

Esteban Méndez, Diana Van Patten

Abstract?This paper studies the role of private sector companies in the development of local amenities. We use evidence from one of the largest multinationals of the 20th century: the United Fruit Company (UFCo). The firm was given a large land concession in Costa Rica—one of the so-called “Banana Republics”—from 1899 to 1984. Using administrative census data with census-block geo-references from 1973 to 2011, we implement a geographic regression discontinuity design that exploits a land assignment that is orthogonal to our outcomes of interest. We find that the firm had a positive and persistent effect on living standards. Company documents explain that a key concern at the time was to attract and maintain a sizable workforce, which induced the firm to invest heavily in local amenities—like the development of education and health infrastructure—that can account for our result. Consistent with this mechanism, we show, empirically and through a proposed model, that the firm's investment efforts increase with worker mobility.

本文研究了私營部門公司在當?shù)鼗A設施開發(fā)中的作用。我們使用20世紀最大的跨國公司之一：聯(lián)合水果公司（UFCo）的證據(jù)。從1899年到1984年，該公司在哥斯達黎加（所謂的“香蕉共和國”之一）獲得了大量土地特許權。使用1973年至2011年的人口普查區(qū)塊地理參考的行政人口普查數(shù)據(jù)，我們實現(xiàn)了地理回歸不連續(xù)性設計，該設計利用了與我們感興趣的結果正交的土地分配。我們發(fā)現(xiàn)該公司對生活水平產生了積極而持久的影響。公司文件解釋說，當時的一個關鍵問題是吸引和維持大量的勞動力，這促使公司大力投資當?shù)氐谋憷O施 - 如教育和衛(wèi)生基礎設施的發(fā)展 - 這可以解釋我們的結果。與這一機制一致，我們通過經驗并通過提出的模型表明，公司的投資努力隨著工人的流動性而增加。

7.Market Competition and Political Influence: An Integrated Approach

市場競爭與政治影響：一個綜合方法

Steven Callander, Dana Foarta, Takuo Sugaya

Abstract?The operation of markets and of politics are in practice deeply intertwined. Political decisions set the rules of the game for market competition and, conversely, market competitors participate in and influence political decisions. We develop an integrated model to capture the circularity between the two domains. We show that a positive feedback loop emerges such that market power begets political power, and political power begets market power, but that this feedback loop is bounded. With too much market power, the balance between politics and markets itself becomes lopsided and this drives a wedge between the interests of a policymaker and the dominant firm. Although such a wedge would seem pro-competitive, we show how it can exacerbate the static and dynamic inefficiency of market outcomes. More generally, our model demonstrates that intuitions about market competition can be upended when competition is intermediated by a strategic policymaker.

市場與政治的運行在實踐中是緊密交織在一起的。政治決策為市場競爭制定了游戲規(guī)則，相反，市場競爭者參與并影響政治決策。我們開發(fā)了一個集成模型來捕捉兩個領域之間的循環(huán)性。結果表明，出現(xiàn)了一個正反饋循環(huán)，使得市場力量產生政治權力，政治權力產生市場力量，但這個反饋循環(huán)是有界的。由于市場力量過大，政治和市場之間的平衡本身就會變得不平衡，這在政策制定者和占主導地位的公司的利益之間造成了楔子。盡管這樣的楔子看起來有利于競爭，但我們展示了它如何加劇市場結果的靜態(tài)和動態(tài)低效率。更一般地說，我們的模型表明，當競爭由戰(zhàn)略決策者進行中介時，關于市場競爭的直覺可以被顛覆。

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8.Productivity Dispersion, Between-Firm Competition, and the Labor Share

生產率分散、企業(yè)間競爭與勞動份額

émilien Gouin-Bonenfant

Abstract?I study the effect of labor market imperfections on the labor share in a tractable model that emphasizes the interaction between productivity dispersion and firm competition for workers. I calibrate the model using administrative data covering the universe of firms in Canada from 2000 to 2015. As in the data, most firms have a high labor share, yet the aggregate labor share is low due to the disproportionate effect of a small fraction of large, highly productive firms. I find that a rise in the dispersion of firm productivity causes the aggregate labor share to decline in favor of firm profits. The mechanism is that productivity dispersion effectively shields high-productivity firms from wage competition. Regression evidence from cross-country and cross-industry data supports both the model prediction and mechanism.

通過強調生產率分散與企業(yè)競爭之間相互作用的易處理模型，本文研究了勞動力市場不完善對勞動份額的影響。我使用涵蓋2000年至2015年加拿大公司范圍的行政數(shù)據(jù)來校準模型。與數(shù)據(jù)一樣，大多數(shù)公司的勞動力份額很高，但由于一小部分大型高生產率公司的不成比例的影響，總勞動力份額很低。我發(fā)現(xiàn)，企業(yè)生產率分散度的上升會導致總勞動份額下降，有利于企業(yè)利潤。其機制是，生產率分散有效地保護了高生產率企業(yè)免受工資競爭的影響。來自跨國和跨行業(yè)數(shù)據(jù)的回歸證據(jù)支持模型預測和機制。

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9 The Converse Envelope Theorem

反包絡定理

Ludvig Sinander

Abstract?I prove an envelope theorem with a converse: the envelope formula is equivalent to a first-order condition. Like Milgrom and Segal's (2002) envelope theorem, my result requires no structure on the choice set. I use the converse envelope theorem to extend to general outcomes and preferences the canonical result in mechanism design that any increasing allocation is implementable, and apply this to selling information.

我從一個反面證明了一個包絡定理：包絡公式等價于一階條件。就像Milgrom和Segal（2002）的包絡定理一樣，我的結果不需要選擇集的結構。我使用逆包絡定理將機制設計中的規(guī)范結果擴展到一般結果和偏好，即任何增加的分配都是可實施的，并將其應用于銷售信息。

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10. A Negishi Approach to Recursive Contracts

遞歸合約的“根岸”方法

Gaetano Bloise, Paolo Siconolfi

Abstract?In this paper, we argue that a large class of recursive contracts can be studied by means of the conventional Negishi method. A planner is responsible for prescribing current actions along with a distribution of future utility values to all agents, so as to maximize their weighted sum of utilities. Under convexity, the method yields the exact efficient frontier. Otherwise, the implementation requires contracts be contingent on publicly observable random signals uncorrelated to fundamentals. We also provide operational first-order conditions for the characterization of efficient contracts. Finally, we compare extensively our approach with the dual method established in the literature.

本文認為，利用傳統(tǒng)的根岸方法可以研究一大類遞歸契約。計劃者負責規(guī)定當前行動以及向所有代理分配未來效用值，以便最大化其效用加權和。在凸性下，該方法產生精確的有效邊界。否則，實現(xiàn)要求合約取決于與基本面無關的可公開觀察的隨機信號。我們還為有效合同的表征提供操作一階條件。最后，我們將我們的方法與文獻中建立的雙重方法進行了廣泛的比較。

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11.Learning From Reviews: The Selection Effect and the Speed of Learning

從評論中學習：選擇效果和學習速度

Daron Acemoglu, Ali Makhdoumi, Azarakhsh Malekian, Asuman Ozdaglar

Abstract?This paper develops a model of Bayesian learning from online reviews and investigates the conditions for learning the quality of a product and the speed of learning under different rating systems. A rating system provides information about reviews left by previous customers. observe the ratings of a product and decide whether to purchase and review it. We study learning dynamics under two classes of rating systems: full history, where customers see the full history of reviews, and summary statistics, where the platform reports some summary statistics of past reviews. In both cases, learning dynamics are complicated by a selection effect—the types of users who purchase the good, and thus their overall satisfaction and reviews depend on the information available at the time of purchase. We provide conditions for complete learning and characterize and compare its speed under full history and summary statistics. We also show that providing more information does not always lead to faster learning, but strictly finer rating systems do.

摘要 本文建立了在線評論的貝葉斯學習模型，考察了不同評分體系下學習產品質量的條件和學習速度。評級系統(tǒng)提供有關以前客戶留下的評論的信息。觀察產品的評級，并決定是否購買和評論它。我們在兩類評級系統(tǒng)下研究學習動態(tài)：完整歷史記錄，客戶可以看到評論的完整歷史記錄，以及摘要統(tǒng)計信息，平臺報告過去評論的一些摘要統(tǒng)計信息。在這兩種情況下，學習動態(tài)都因選擇效應而變得復雜——購買商品的用戶類型，因此他們的整體滿意度和評論取決于購買時可用的信息。我們?yōu)橥暾膶W習提供條件，并在完整的歷史記錄和匯總統(tǒng)計下表征和比較其速度。我們還表明，提供更多信息并不總是能加快學習速度，但嚴格來說，更精細的評級系統(tǒng)可以。

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12. Spatial Correlation Robust Inference

空間相關性穩(wěn)健推理

Ulrich K. Müller, Mark W. Watson

Abstract?We propose a method for constructing confidence intervals that account for many forms of spatial correlation. The interval has the familiar “estimator plus and minus a standard error times a critical value” form, but we propose new methods for constructing the standard error and the critical value. The standard error is constructed using population principal components from a given “worst-case” spatial correlation model. The critical value is chosen to ensure coverage in a benchmark parametric model for the spatial correlations. The method is shown to control coverage in finite sample Gaussian settings in a restricted but nonparametric class of models and in large samples whenever the spatial correlation is weak, that is, with average pairwise correlations that vanish as the sample size gets large. We also provide results on the efficiency of the method.

摘要 提出了一種考慮多種空間相關性的置信區(qū)間構造方法。區(qū)間具有熟悉的“估計量正減標準誤差乘以臨界值”形式，但我們提出了構造標準誤差和臨界值的新方法。標準誤差是使用來自給定“最壞情況”空間相關模型的總體主成分構建的。選擇臨界值以確保空間相關性的基準參數(shù)模型中的覆蓋范圍。該方法被證明可以在有限但非參數(shù)類別的模型中控制有限樣本高斯設置中的覆蓋率，并且在空間相關性較弱時控制大樣本中的覆蓋率，即平均成對相關性隨著樣本量變大而消失。我們還提供有關該方法效率的結果。

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13. Achieving Scale Collectively

集體實現(xiàn)規(guī)?；?/p>

Vittorio Bassi, Raffaela Muoio, Tommaso Porzio, Ritwika Sen, Esau Tugume

Abstract?Many firms in developing countries could be too small to adopt modern technology embodied in expensive production machines. This paper shows that rental market interactions allow these small firms to increase their effective scale and mechanize production. We conduct a survey of manufacturing firms in Uganda, which uncovers an active rental market for large machines between small firms in informal clusters. We then build an equilibrium model of firm behavior and estimate it with our data. We find that the rental market is quantitatively important for mechanization and productivity since it provides a workaround for other market imperfections that keep firms small. The rental market also shapes the effectiveness of development policies to foster mechanization, such as subsidies to purchase machines. Overall, our results point to the importance of taking into account firm-to-firm interactions within informal clusters to understand technology adoption in low income countries: focusing on the small scale of firms in isolation might be misleading.

發(fā)展中國家的許多公司可能規(guī)模太小，無法采用昂貴的生產機器所體現(xiàn)的現(xiàn)代技術。本文表明，租賃市場的互動使這些小公司能夠擴大其有效規(guī)模并實現(xiàn)生產機械化。我們對烏干達的制造公司進行了一項調查，發(fā)現(xiàn)非正式集群中的小公司之間的大型機器租賃市場活躍。然后，我們建立一個公司行為的均衡模型，并用我們的數(shù)據(jù)對其進行估計。我們發(fā)現(xiàn)，租賃市場在數(shù)量上對機械化和生產力很重要，因為它為其他使公司規(guī)模較小的市場缺陷提供了一種解決方法。租賃市場也決定了促進機械化的發(fā)展政策的有效性，例如對購買機器的補貼。總體而言，我們的研究結果表明，在了解低收入國家的技術采用方面，必須考慮非正式集群內的企業(yè)與企業(yè)之間的互動：孤立地關注小規(guī)模企業(yè)可能會產生誤導。

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