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解析作者 | 唧唧堂经济金融学写作小组：
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1、论描述性统计数据在结构性估计中的信息量
作者提出了一种正式确定描述性分析和结构性估计之间关系的方法。曾有学者提出一个利息结构量c的估计值ĉ，这个估计值在某个基础模型下是完全无偏的或渐进无偏的。同时，该学者还提出了一个描述性统计量ŷ来估计在该基础模型下与c相关的数据分布的特征y。然而，另位学者基于上述基础模型，构建了一个限制更少的新模型，在新模型下，估计值ĉ可能会有偏差。作者对这一新模型进行改进，提出了一个可以减少最大估计偏差的约束，而这一约束要求新模型遵守基础模型中c和 y 之间特定的关系。作者的主要结果表明，最大偏差能在多大程度上减少只取决于一个量，作者称之为ŷ 对ĉ的信息量。即使对于复杂的模型，信息量也可以很容易地估计出来。因此，作者建议研究人员在进行描述性分析的同时，也要报告估计的信息量，作者随后以最近三篇论文的应用为例进行说明。
摘要原文：We propose a way to formalize the relationship between descriptive analysis and structural estimation. A researcher reports an estimate ĉ of a structural quantity of interest c that is exactly or asymptotically unbiased under some base model. The researcher also reports descriptive statistics that estimate features γ of the distribution of the data that are related to c under the base model. A reader entertains a less restrictive model that is local to the base model, under which the estimate ĉ may be biased. We study the reduction in worst‐case bias from a restriction that requires the reader's model to respect the relationship between c and γ specified by the base model. Our main result shows that the proportional reduction in worst‐case bias depends only on a quantity we call the informativeness of for ĉ. Informativeness can be easily estimated even for complex models. We recommend that researchers report estimated informativeness alongside their descriptive analyses, and we illustrate with applications to three recent papers.
参考文献：Isaiah Andrews, Matthew Gentzkow, Jesse M. Shapiro. On the Informativeness of Descriptive Statistics for Structural Estimates. Econometrica.
摘要原文：We exhibit a natural environment, social learning among heterogeneous agents, where even slight misperceptions can have a large negative impact on long‐run learning outcomes. We consider a population of agents who obtain information about the state of the world both from initial private signals and by observing a random sample of other agents' actions over time, where agents' actions depend not only on their beliefs about the state but also on their idiosyncratic types (e.g., tastes or risk attitudes). When agents are correct about the type distribution in the population, they learn the true state in the long run. By contrast, we show, first, that even arbitrarily small amounts of misperception about the type distribution can generate extreme breakdowns of information aggregation, where in the long run all agents incorrectly assign probability 1 to some fixed state of the world, regardless of the true underlying state. Second, any misperception of the type distribution leads long‐run beliefs and behavior to vary only coarsely with the state, and we provide systematic predictions for how the nature of misperception shapes these coarse long‐run outcomes. Third, we show that how fragile information aggregation is against misperception depends on the richness of agents' payoff‐relevant uncertainty; a design implication is that information aggregation can be improved by simplifying agents' learning environment. The key feature behind our findings is that agents' belief‐updating becomes “decoupled” from the true state over time. We point to other environments where this feature is present and leads to similar fragility results.
参考文献：Mira Frick, Ryota Iijima, Yuhta Ishii. Misinterpreting Others and the Fragility of Social Learning. Econometrica.
3、边境文化：美国“坚固的个人主义”的根源和持久性
向西移动的定居边境的存在，塑造了美国早期的历史。1893年，历史学家弗雷德里克-杰克逊-特纳（Frederick Jackson Turner）提出了一个著名的论点，即美国的边疆培养了个人主义。作者研究了 "边疆论"，并确定其对文化和政治的长期影响。作者追踪了1790-1890年期间的边疆，并构建了一个新颖的、县级的“总边疆经历”（TFE）衡量标准。从历史上看，边疆地区具有独特的人口结构和更大的个人主义。在边境确定后的很长一段时间里，具有更大TFE的县表现出更普遍的个人主义和反对再分配。这种模式跨越了美国已知的分界线，包括城市-农村和北-南。作者提供了关于边疆文化根源的证据，确定了选择性移民和边疆环境对个人主义的因果效应。总的来说，作者的研究结果使大家对边疆长期的粗鲁的个人主义传统有了新的认识。
摘要原文：The presence of a westward‐moving frontier of settlement shaped early U.S. history. In 1893, the historian Frederick Jackson Turner famously argued that the American frontier fostered individualism. We investigate the “frontier thesis” and identify its long‐run implications for culture and politics. We track the frontier throughout the 1790–1890 period and construct a novel, county‐level measure of total frontier experience (TFE). Historically, frontier locations had distinctive demographics and greater individualism. Long after the closing of the frontier, counties with greater TFE exhibit more pervasive individualism and opposition to redistribution. This pattern cuts across known divides in the United States, including urban–rural and north–south. We provide evidence on the roots of frontier culture, identifying both selective migration and a causal effect of frontier exposure on individualism. Overall, our findings shed new light on the frontier's persistent legacy of rugged individualism.
参考文献：Samuel Bazzi, Martin Fiszbein, Mesay Gebresilasse. Frontier Culture: The Roots and Persistence of “Rugged Individualism” in the United States. Econometrica.
摘要原文：We design a labor market experiment to compare demand‐ and supply‐side policies to tackle youth unemployment, a key issue in low‐income countries. The experiment tracks 1700 workers and 1500 firms over four years to compare the effect of offering workers either vocational training (VT) or firm‐provided training (FT) for six months in a common setting where youth unemployment is above 60%. Relative to control workers, we find that, averaged over three post‐intervention years, FT and VT workers: (i) enjoy large and similar upticks in sector‐specific skills, (ii) significantly improve their employment rates, and (iii) experience marked improvements in an index of labor market outcomes. These averages, however, mask differences in dynamics: FT gains materialize quickly but fade over time, while VT gains emerge slowly but are long‐lasting, leading VT worker employment and earning profiles to rise above those of FT workers. Estimating a job ladder model of worker search reveals the key reason for this: VT workers receive significantly higher rates of job offers when unemployed, thus hastening their movement back into work. This likely stems from the fact that the skills of VT workers are certified and therefore can be demonstrated to potential employers. Tackling youth unemployment by skilling youth using vocational training pre‐labor market entry therefore appears to be more effective than incentivizing firms through wage subsidies to hire and train young labor market entrants.
参考文献: Livia Alfonsi, Oriana Bandiera, Vittorio Bassi, Robin Burgess, Imran Rasul, Munshi Sulaiman, Anna Vitali. Tackling Youth Unemployment: Evidence From a Labor Market Experiment in Uganda. Econometrica.
摘要原文: The correlation between productivity and competition is an oft observed but incompletely understood result. Some suggest that there is a treatment effect of competition on measured productivity, for example, through a reduction of managerial slack. Others argue that greater competition makes unproductive establishments exit by reallocating demand to their productive rivals, raising observed average productivity via selection. I study the ready‐mix concrete industry and offer three perspectives on this ambivalence. First, using a standard decomposition approach, I look for evidence of greater reallocation of demand to productive plants in more competitive markets. Second, I model the establishment exit decision and construct a semiparametric selection correction to quantify the empirical significance of treatment and selection. Finally, I use a grouped instrumental variable quantile regression to test the distributional predictions of the selection hypothesis. I find no evidence for greater selection or reallocation in more competitive markets; instead, all three results suggest that measured productivity responds directly to competition. Potential channels include specialization and managerial inputs.
参考文献: Matthew Backus. Why Is Productivity Correlated With Competition? Econometrica.
摘要原文: We study games in which a network mediates strategic spillovers and externalities among the players. How does a planner optimally target interventions that change individuals' private returns to investment? We analyze this question by decomposing any intervention into orthogonal principal components, which are determined by the network and are ordered according to their associated eigenvalues. There is a close connection between the nature of spillovers and the representation of various principal components in the optimal intervention. In games of strategic complements (substitutes), interventions place more weight on the top (bottom) principal components, which reflect more global (local) network structure. For large budgets, optimal interventions are simple—they essentially involve only a single principal component.
参考文献: Andrea Galeotti, Benjamin Golub, Sanjeev Goyal. Targeting Interventions in Networks. Econometrica.
摘要原文: We study the role of financial frictions and firm heterogeneity in determining the investment channel of monetary policy. Empirically, we find that firms with low default risk—those with low debt burdens and high “distance to default”— are the most responsive to monetary shocks. We interpret these findings using a heterogeneous firm New Keynesian model with default risk. In our model, low‐risk firms are more responsive to monetary shocks because they face a flatter marginal cost curve for financing investment. The aggregate effect of monetary policy may therefore depend on the distribution of default risk, which varies over time.
参考文献: Pablo Ottonello, Thomas Winberry. Financial Heterogeneity and the Investment Channel of Monetary Policy. Econometrica.
摘要原文: Differences in regulated pharmaceutical prices within the European Economic Area create arbitrage opportunities that pharmacy retailers can access through parallel imports. For prescription drugs under patent, parallel trade affects the sharing of profits among an innovating pharmaceutical company, retailers, and parallel traders. We develop a structural model of demand and supply in which retailers can choose the set of goods to sell, thus foreclosing consumers' access to less profitable drugs. This allows retailers to bargain and obtain lower wholesale prices from the manufacturer and parallel trader. With detailed transaction data from Norway, we identify a demand model with unobserved choice sets using retail‐side conditions for optimal assortment decisions of pharmacies. We find that retailer incentives play a significant role in fostering parallel trade penetration and that banning parallel imports would benefit manufacturers as well as prevent pharmacies from foreclosing the manufacturer's product. Finally, in the case of the statin market in Norway, we show that it would be possible to decrease spending and increase profits of the original manufacturer through lump sum transfers associated with a lower reimbursement price, thus decreasing price differentiation across countries.
参考文献: Pierre Dubois, Morten Sæthre. On the Effect of Parallel Trade on Manufacturers' and Retailers' Profits in the Pharmaceutical Sector. Econometrica.
摘要原文: Asymptotic bootstrap validity is usually understood as consistency of the distribution of a bootstrap statistic, conditional on the data, for the unconditional limit distribution of a statistic of interest. From this perspective, randomness of the limit bootstrap measure is regarded as a failure of the bootstrap. We show that such limiting randomness does not necessarily invalidate bootstrap inference if validity is understood as control over the frequency of correct inferences in large samples. We first establish sufficient conditions for asymptotic bootstrap validity in cases where the unconditional limit distribution of a statistic can be obtained by averaging a (random) limiting bootstrap distribution. Further, we provide results ensuring the asymptotic validity of the bootstrap as a tool for conditional inference, the leading case being that where a bootstrap distribution estimates consistently a conditional (and thus, random) limit distribution of a statistic. We apply our framework to several inference problems in econometrics, including linear models with possibly nonstationary regressors, CUSUM statistics, conditional Kolmogorov–Smirnov specification tests and tests for constancy of parameters in dynamic econometric models.
参考文献: Giuseppe Cavaliere, Iliyan Georgiev. Inference Under Random Limit Bootstrap Measures. Econometrica.
摘要原文: We study games of incomplete information as both the information structure and the extensive form vary. An analyst may know the payoff‐relevant data but not the players' private information, nor the extensive form that governs their play. Alternatively, a designer may be able to build a mechanism from these ingredients. We characterize all outcomes that can arise in an equilibrium of some extensive form with some information structure. We show how to specialize our main concept to capture the additional restrictions implied by extensive‐form refinements.
参考文献: Laura Doval, Jeffrey C. Ely. Sequential Information Design. Econometrica.
摘要原文: We study the behavior of the U.S. labor share over the past 90 years. We find that the observed decline of the labor share is entirely explained by the capitalization of intellectual property products in the national income and product accounts.
摘要原文: I study a mechanism design problem in which a designer allocates a single good to one of several agents, and the mechanism is followed by an aftermarket—a post‐mechanism game played between the agent who acquired the good and third‐party market participants. The designer has preferences over final outcomes, but she cannot design the aftermarket. However, she can influence its information structure by publicly disclosing information elicited from the agents by the mechanism.
I introduce a class of allocation and disclosure rules, called cutoff rules, that disclose information about the buyer's type only by revealing information about the realization of a random threshold (cutoff) that she had to outbid to win the object. When there is a single agent in the mechanism, I show that the optimal cutoff mechanism offers full privacy to the agent. In contrast, when there are multiple agents, the optimal cutoff mechanism may disclose information about the winner's type; I provide sufficient conditions for optimality of simple designs. I also characterize aftermarkets for which restricting attention to cutoff mechanisms is without loss of generality in a subclass of all feasible mechanisms satisfying additional conditions.
参考文献: Piotr Dworczak. Mechanism Design With Aftermarkets: Cutoff Mechanisms. Econometrica.
