编者按：美国全国经济研究所（NBER）是美国最大的经济学研究组织，其发布的工作论文代表着经济学研究最新的成果，每周一发布新论文。本周（10.7-10.13）共发布 26 篇新工作论文，本期将会推最后 9 篇论文的题目与摘要，供读者学习。
学术财经研究团队翻译。
今日在，明日消失？探究幼儿教育项目效果衰退现象
John A. List and Haruka Uchida #33027
Abstract: An unsettling stylized fact is that decorated early childhood education programs improve cognitive skills in the short-term, but lose their efficacy after a few years. We implement a field experiment with two stages of randomization to explore the underpinnings of the fade-out effect. We first randomly assign preschool access to children, and then partner with the local school district to randomly assign the same children to classmates throughout elementary school. We find that the fade-out effect is critically-linked to the share of classroom peers assigned to preschool access—with enough treated peers the classic fade-out effect is muted. Our results highlight a paradoxical insight: while the fade-out effect has been viewed as a devastating critique of early childhood programs, our results highlight that fade-out is a key rationale for providing early education to all children. This is because human capital accumulation is inherently a social activity, leading early education programs to deliver their largest benefits at scale when everyone receives such programs.
摘要：一个令人不安的典型事实是，著名的幼儿教育项目在短期内能提升认知技能，但其效果在几年后逐渐消失。我们通过实施一个包含两阶段随机分配的现场实验，探讨这种效果衰退现象的根源。首先，我们随机为儿童分配学前教育的机会，然后与当地学区合作，随机将这些儿童分配到小学的班级同学中。我们的研究发现，效果衰退现象与同班同学中获得学前教育机会的比例密切相关——当同班同学中接受过学前教育的人数足够多时，经典的效果衰退现象就会减弱。我们的结果揭示了一个看似矛盾的见解：尽管效果衰退常被视为对幼儿教育项目的严重批评，我们的结果却表明，效果衰退是为所有儿童提供早期教育的关键理由。这是因为人力资本的积累本质上是一种社会活动，早期教育项目在大规模普及时才能带来最大的益处。
交易量阿尔法
Ruslan Goyenko, Bryan T. Kelly, Tobias J. Moskowitz, Yinan Su, and Chao Zhang #33037
Abstract: Portfolio optimization focuses on risk and return prediction, yet implementation costs critically matter. Predicting trading costs is challenging because costs depend on trade size and trader identity, thus impeding a generic solution. We focus on a component of trading costs that applies universally – trading volume. Individual stock trading volume is highly predictable, especially with machine learning. We model the economic benefits of predicting volume through a portfolio framework that trades off tracking error versus net-of-cost performance – translating volume prediction into net-of-cost alpha. The economic benefits of predicting individual stock volume are as large as those from stock return predictability.
摘要：投资组合优化通常聚焦于风险和回报的预测，但实施成本也至关重要。预测交易成本具有挑战性，因为成本取决于交易规模和交易者身份，因此难以找到通用的解决方案。我们关注一个普遍适用的交易成本组成部分——交易量。个股的交易量高度可预测，尤其是通过机器学习。我们通过一个投资组合框架来建模预测交易量的经济效益，该框架权衡跟踪误差与扣除成本后的表现，将交易量预测转化为扣除成本后的阿尔法收益。预测个股交易量的经济效益与股票回报预测的收益同样显著。
适用于重复横截面的灵活异质性处理效应DiD估计方法
Partha Deb, Edward C. Norton, Jeffrey M. Wooldridge, and Jeffrey E. Zabel #33026
Abstract: This paper proposes a method to estimate treatment effects in difference-in-differences designs in which the treatment start is staggered over time and treatment effects are heterogeneous by group, time, and covariates, and when the data are repeated cross-sections. We show that a linear-in-parameters regression specification with a sufficiently flexible functional form consisting of group-by-time treatment effects, two-way fixed effects, and interaction terms yields consistent estimates of heterogeneous treatment effects under general conditions. The estimates are efficient and aggregation of treatment effects and inference are straightforward. We call it FLEX, because it is a flexible linear model estimated by OLS with covariates (X). We illustrate the use of FLEX with two empirical examples and provide comparisons to other recently derived estimators.
摘要：本文提出了一种用于估计DiD设计中的处理效应的方法，该设计中处理的开始时间是分阶段的，并且处理效应在群体、时间和协变量之间存在异质性，且数据为重复横截面数据。我们展示了一种参数线性回归规范，该规范包含群体与时间的处理效应、双向固定效应和交互项，具有足够灵活的函数形式，可以在一般条件下提供异质性处理效应的一致估计。这些估计是有效的，处理效应的加总和推断也相对简单。我们称之为FLEX，因为它是一种通过普通最小二乘法（OLS）与协变量（X）进行估计的灵活线性模型。我们通过两个实证例子展示了FLEX的使用，并与最近提出的其他估计方法进行了比较。
威权主义下对民主的误解与需求
Daron Acemoglu, Cevat Giray Aksoy, Ceren Baysan, Carlos Molina, and Gamze Zeki #33018
Abstract: This paper investigates whether enduring authoritarian regimes are in part rooted in the population’s misperceptions about their social and economic costs—as opposed to a general preference for authoritarianism. We explore this question using online and field experiments in the context of Türkiye’s May 2023 presidential and parliamentary elections. We confirm that voters, especially those supporting the incumbent authoritarian government systematically underestimate the extent to which democracy and media freedom have been eroded in Türkiye and their usefulness in dealing with natural disasters and corruption (two salient issues in Türkiye). We find that providing (accurate) information about the state and implications of democracy and media freedom have significant effects on beliefs and increase the likelihood of voting for the opposition by about 3.7 percentage points (6.2 percent) in the online experiment. In the field experiment, we estimate similarly-sized impacts on the ballot-box level vote share—with the information treatment leading to a 2.4 percentage point (4.4 percent) increase in the opposition’s vote share. Interestingly, both in the field and online, the results are driven not by further mobilizing opposition supporters, but by influencing those likely to vote for the governing coalition and those holding more misperceived beliefs about democracy and media freedom in Türkiye. The evidence suggests that at least part of the support for authoritarian regimes may be coming from misperceptions about their institutions and policies, and may be more malleable than typically presumed.
摘要：本文研究了长期存在的威权政权是否部分根源于民众对其社会和经济成本的误解，而非普遍的威权偏好。我们通过线上和实地实验，探讨了这一问题，以2023年5月土耳其总统和议会选举为背景。我们确认，选民，特别是支持现任威权政府的选民，系统性地低估了土耳其民主和媒体自由被侵蚀的程度，以及民主和媒体自由在应对自然灾害和腐败（两个在土耳其非常突出的议题）方面的作用。我们的研究发现，提供关于民主和媒体自由现状及其影响的准确信息，显著改变了选民的信念，并使他们支持反对派的可能性在线上实验中增加了约3.7个百分点（6.2%）。在实地实验中，我们估算了类似规模的影响，信息干预使反对派的票数份额增加了2.4个百分点（4.4%）。有趣的是，无论是在实地还是线上，这些结果并非通过进一步动员反对派支持者实现，而是通过影响那些倾向于投票给执政联盟的选民以及那些对土耳其民主和媒体自由持有更多误解的选民实现的。证据表明，至少部分对威权政权的支持可能源于对其制度和政策的误解，这种支持比通常认为的更易受外界影响。
父母收入与普惠学前教育的回报
John Eric Humphries, Christopher Neilson, Xiaoyang Ye, and Seth D. Zimmerman #33038
Abstract: This paper asks whether universal pre-kindergarten (UPK) raises parents' earnings and how much these earnings effects matter for evaluating the economic returns to UPK programs. Using a randomized lottery design, we estimate the effects of enrolling in a full-day UPK program in New Haven, Connecticut on parents' labor market outcomes as well as educational expenditures and children's academic performance. During children's pre-kindergarten years, UPK enrollment increases weekly childcare coverage by 11 hours. Enrollment has limited impacts on children's academic outcomes between kindergarten and 8th grade, likely due to a combination of rapid effect fadeout and substitution away from other programs of similar quality but with shorter days. In contrast, parents work more hours, and their earnings increase by 21.7%. Parents' earnings gains persist for at least six years after the end of pre-kindergarten. Excluding impacts on children, each dollar of net government expenditure yields $5.51 in after-tax benefits for families, almost entirely from parents' earnings gains. This return is large compared to other labor market policies. Conversely, excluding earnings gains for parents, each dollar of net government expenditure yields only $0.46 to $1.32 in benefits, lower than many other education and children's health interventions. We conclude that the economic returns to investing in UPK are high, largely because of full-day UPK's effectiveness as an active labor market policy.
摘要：本文探讨了普惠学前教育（UPK）是否能提高父母的收入，以及这些收入效应在评估UPK项目经济回报中有多大影响。通过使用随机抽签设计，我们估计了在康涅狄格州纽黑文全日制UPK项目的入学对父母劳动力市场结果、教育支出以及儿童学业表现的影响。研究发现，在儿童学前年龄段，UPK入学使每周的托儿时间增加了11小时。入学对儿童在幼儿园到8年级期间的学业表现影响有限，可能是由于效果快速衰退以及替代了其他质量相似但上课时间较短的项目。相比之下，父母工作时间增加，收入增长了21.7%，并且在学前教育结束后的至少六年内，父母收入的增长持续存在。若不考虑对儿童的影响，政府每净支出一美元为家庭带来5.51美元的税后收益，几乎全部来自父母的收入增长。相比之下，若不计算父母的收入增长，政府每净支出一美元仅带来0.46美元到1.32美元的收益，低于许多其他教育和儿童健康干预项目的回报。我们得出结论，投资于UPK的经济回报很高，主要原因是全日制UPK作为一项积极的劳动力市场政策非常有效。
《排华法案》对美国西部经济发展的影响
Joe Long, Carlo Medici, Nancy Qian, and Marco Tabellini #33019
Abstract: This paper investigates the economic consequences of the 1882 Chinese Exclusion Act, which banned immigration from China to the United States. The Act reduced the number of Chinese workers of all skill levels residing in the U.S. It also reduced the labor supply and the quality of jobs held by white and U.S.-born workers, the intended beneficiaries of the Act, and reduced manufacturing output. The results suggest that the Chinese Exclusion Act slowed economic growth in western states until at least 1940.
摘要：本文探讨了1882年《排华法案》的经济后果，该法案禁止中国人移民到美国。法案减少了所有技能水平的华裔工人在美国的数量，同时减少了白人和美国本土工人（该法案的预期受益者）的劳动力供应和工作质量，并降低了制造业产出。研究结果表明，《排华法案》减缓了美国西部各州的经济增长，直到至少1940年。
动态优化的序列实验（DOSE）用于估计经济偏好参数
Jonathan Chapman, Erik Snowberg, Stephanie W. Wang, and Colin Camerer #33013
Abstract: We introduce DOSE—Dynamically Optimized Sequential Experimentation—to elicit preference parameters. DOSE starts with a model of preferences and a prior over the parameters of that model, then dynamically chooses a customized question sequence for each participant according to an experimenter-selected information criterion. After each question, the prior is updated, and the posterior is used to select the next, informationally-optimal, question. Simulations show that DOSE produces parameter estimates that are approximately twice as accurate as those from established elicitation methods. DOSE estimates of individual-level risk and time preferences are also more accurate, more stable over time, and faster to administer in a large representative, incentivized survey of the U.S. population (N = 2,000). By reducing measurement error, DOSE identifies a stronger relationship between risk aversion and cognitive ability than other elicitation techniques. DOSE thus provides a flexible procedure that facilitates the collection of incentivized preference measures in the field.
摘要：我们介绍了动态优化的序列实验（DOSE）方法，用于引出偏好参数。DOSE以偏好模型及其参数的先验分布为起点，根据实验者选择的信息准则，为每个参与者动态选择定制的问题序列。每回答一个问题后，先验分布会更新，后验分布则用于选择下一个信息上最优的问题。模拟结果显示，DOSE产生的参数估计比现有的引导方法精度高约两倍。在美国一项大型具有代表性、激励性的调查（N = 2,000）中，DOSE对个体风险和时间偏好的估计也更加准确、稳定且耗时更短。通过减少测量误差，DOSE比其他引导技术更清晰地识别出风险厌恶与认知能力之间的强相关性。因此，DOSE为现场激励性偏好测量提供了一种灵活的程序。
关于政策制定的最优分配
Alessandro Dovis, Rishabh Kirpalani, and Guillaume M. Sublet #33034
Abstract: How should society allocate policy-making between the legislative and the executive branches of government? We analyze a model in which biased and polarized policymakers set policy in response to shocks. We show that policy issues for which the policy-maker bias is small relative to the degree of polarization should be delegated to the legislature, while policy issues where the bias is large should be delegated to the executive. Moreover, when executive delegation is preferred, it is optimal to leave little discretion and impose a narrow mandate. This finding contrasts with conventional wisdom that executive delegation allows for greater flexibility. The main difference between the two institutional settings is the ability to restrict ex post bargaining under executive delegation. Thus, when the bias is large, executive delegation is preferred because it can effectively constrain policymakers' choices. In contrast, when the bias is small, the ability to bargain ex post allows for flexible responses to severe shocks while limiting political risk. We also study the credibility of these institutions and show that while delegating to the legislature is typically credible, executive delegation is typically not when the bias is exogenous but can be when the bias arises from time inconsistency problems.
摘要：社会应如何在立法部门和行政部门之间分配政策制定权？我们分析了一个模型，其中存在偏见和极化的政策制定者根据冲击来制定政策。研究表明，当政策制定者的偏见相对于极化程度较小时，应将政策问题委托给立法部门；而当偏见较大时，应将政策问题委托给行政部门。此外，当行政委托是优选时，最佳做法是给予有限的自由裁量权并设定狭窄的任务授权。此发现与传统观点相反，传统观点认为行政委托允许更大的灵活性。两种制度安排的主要区别在于，行政委托下可以限制事后的谈判。因此，当偏见较大时，行政委托被优选，因为它可以有效地限制政策制定者的选择。相反，当偏见较小时，事后谈判的能力允许对重大冲击做出灵活反应，同时限制政治风险。我们还研究了这些制度的可信度，结果表明，虽然将权力委托给立法部门通常是可信的，但当偏见是外生的情况下，行政委托通常不具备可信度；然而，当偏见源于时间不一致问题时，行政委托可能是可信的。
碳关税101
Claire Brunel and Arik Levinson #33024
Abstract: We evaluate the economic and environmental consequences of taxes on imported goods based on their carbon content. The analysis uses the simplest possible partial equilibrium framework, with one small open economy and a global pollution externality. It relies on graphs of supply and demand, rather than equations or formulas, hoping to reach readers familiar with basic economics. Despite its simplicity, the framework imparts numerous lessons. (1) Absent a domestic price on carbon, a carbon tariff imposes the same costs on domestic consumers as a domestic carbon price, but a carbon tariff also subsidizes domestic pollution. (2) If one small country imposes a carbon tariff, with or without a domestic carbon tax, the economic incidence of the tariff falls on its consumers. (3) If a holdout country joins the rest of the world by enacting its own carbon regulation and consequently imports more from other countries, those increased imports are not “leakage.” They are the cessation of leakage from when the holdout country’s policy was lax. And (4) if other countries do not appropriately regulate emissions, no single small country can use a combination of carbon taxes and carbon tariffs to fully correct the problem caused by its consumers or producers.
摘要：我们评估了基于进口商品碳含量征税的经济和环境影响。分析采用了最简单的局部均衡框架，一个小型开放经济体和全球污染外部性，依赖供需图表，而非方程或公式，以期能够吸引熟悉基础经济学的读者。尽管框架简单，但它传达了多个重要的教训：(1) 如果没有国内的碳定价，碳关税对国内消费者施加的成本与国内碳定价相同，但碳关税同时也补贴了国内污染。(2) 如果一个小国施加碳关税，不论是否伴有国内碳税，关税的经济负担都会落在该国消费者身上。(3) 如果一个滞后国家通过实施自己的碳法规加入全球减排行列，因而从其他国家增加进口，这些增加的进口并不是“泄漏”，而是由于该国政策宽松导致的泄漏的停止。(4) 如果其他国家没有适当管控排放，单个小国无法通过碳税和碳关税的组合来完全纠正其消费者或生产者所导致的问题。
往期精选：
