American Economic Review

We evaluate equity-efficiency trade-offs from admissions quotas by examining effects on output once beneficiaries start producing in the relevant industry. We estimate the impact of abolishing a 40 percent quota for male primary school teachers on their pupils’ long-run outcomes. We combine this reform with the timing of union-bargained teacher retirements to isolate quasi-random variation in male quota teachers. Pupils exposed to male quota teachers transition more smoothly to postcompulsory education and have higher educational attainment and labor force attachment at age 25. Evidence suggests the quota improved the allocation of talent by mending imperfections in the unconstrained selection process. (JEL I21, I23, I28, J16, J24, J45)

本文通过考察配额受益者进入相关行业产出后的效果，评估录取配额中的公平-效率权衡。我们估计了一项取消小学男教师 40% 配额的政策改革对学生长期结果的影响。我们将该改革与工会协商的教师退休时间相结合，以分离出男性配额教师的准随机变动。接触过男性配额教师的学生更顺利地过渡到义务教育后阶段，且在 25 岁时具有更高的教育成就和劳动力市场参与度。证据表明，该配额通过弥补非约束性选拔过程中的缺陷，改善了人才配置。

Do elite colleges help talented students join the social elite or help incumbent elites retain their positions? We combine intergenerationally linked data from Chile with a regression discontinuity design to show that, looking across generations, elite colleges do both. Lower-status individuals who gain admission to elite college programs transform their children’s social environment. Children become more likely to attend high-status private schools and colleges and to live near and befriend high-status peers. In contrast, academic achievement is unaffected. Simulations combining descriptive and quasi-experimental findings show that elite colleges tighten the link between social and human capital while decreasing intergenerational social mobility. (JEL I23, I26, J24, J62, O15, Z13)

精英大学究竟是帮助有才华的学生跻身社会精英阶层，还是帮助现任精英维持其地位？我们将智利的代际关联数据与断点回归设计相结合，发现跨代来看，精英大学同时发挥了这两种作用。获得精英大学录取的低社会地位个体，其子女的社会环境发生了显著转变——更可能入读高地位私立学校和大学，并与高地位同伴为邻为友。相比之下，学业成绩未受影响。结合描述性和准实验发现的模拟显示，精英大学强化了社会资本与人力资本之间的联系，同时降低了代际社会流动性。

Policy choices often create trade-offs between workers and consumers. I examine how foreign competition alters the consumer welfare and domestic employment effects of mergers. I construct a model incorporating consumer demand, endogenous product portfolios, and employment decisions. Applying the model to Whirlpool’s acquisition of Maytag in the appliance industry, I compare the observed merger to a counterfactual acquisition by a foreign buyer. Although Whirlpool’s acquisition decreased consumer welfare by $271 million annually, it preserved 797 domestic jobs. These jobs must therefore be valued at more than $344, 000 per year for the domestic employment benefits to offset the consumer harm. (JEL E24, F23, G34, J30, L13, L68, R23)

政策选择常常在工人与消费者之间形成权衡。本文考察外国竞争如何改变并购对消费者福利和国内就业的影响。我构建了一个包含消费者需求、内生性产品组合和就业决策的模型。将该模型应用于家电行业中惠而浦对美泰克的收购，我将实际并购与假想的外国买家收购进行对比。尽管惠而浦的收购每年使消费者福利减少 2.71 亿美元，但它保留了 797 个国内就业岗位。因此，这些岗位每年必须被赋予超过 34.4 万美元的价值，国内就业收益才能抵消消费者损失。

This paper examines the effects of privatizing social health insurance. We exploit a natural experiment in Medicaid, wherein nearly 100,000 enrollees were randomly assigned between a publicly operated fee-for-service system and private managed care. Managed care reduced costs by 5.6 percent via cost-effective substitutions among prescription drugs and via lower prices for outpatient services. We present evidence that pharmacy utilization management was the key mechanism reducing overuse and encouraging substitution to lower-cost drugs without decreasing observed quality. In contrast, privatizing medical benefits led to only modest savings and was associated with decreased health care quality and consumer satisfaction. (JEL G22, H41, I13, I18, I38)

本文研究社会医疗保险私有化的效应。我们利用医疗补助（Medicaid）中的一项自然实验，其中近 10 万名参保者被随机分配到公共运营的服务付费体系和私人管理式医疗保险之间。管理式医疗保险通过处方药之间的成本效益替代和门诊服务的更低价格，将成本降低了 5.6%。我们提供的证据表明，药品利用管理是减少过度使用和鼓励替代低成本药物的关键机制，同时未降低观察到的质量。相比之下，将医疗福利私有化仅带来适度节省，并伴随医疗保健质量和消费者满意度的下降。

We examine how social interactions and friendships shape students’ political opinions in a natural experiment at Sciences Po, a leading French university specializing in social and political sciences. The quasi-random assignment of students into short-term integration groups before their academic curriculum reduces political opinion gaps and fosters friendship formation. Using same-group membership as an instrumental variable for friendship, we find that friendship reduces opinion differences by 44 percent of the mean opinion gap. Our evidence supports a homophily-enforced mechanism: Friendships form among initially politically similar students, leading them to join political associations together, reinforcing their similarity. (JEL C93, D72, Z13)

我们利用法国顶尖社科大学巴黎政治学院（Sciences Po）的一项自然实验，考察社会互动和友谊如何塑造学生的政治观点。在学术课程开始前，学生被准随机分配到短期融合小组，此举缩小了政治观点差距并促进了友谊形成。使用同组成员身份作为友谊的工具变量，我们发现友谊使观点差异减少了平均观点差距的 44%。我们的证据支持一个同质性强化机制：友谊在初始政治立场相似的学生之间形成，进而促使他们一起加入政治社团，强化了彼此的观点相似性。

Item-level transactions data yield cost-of-living indices that can account for quality change and consumer substitution. Transactions data require confronting the rapid turnover of items because prices of new and existing products are interrelated in equilibrium. This paper evaluates multiple approaches to measuring quality change at scale. It shows that a hedonic superlative approach—using econometrics or machine learning for hedonic estimation combined with index formulas that require simultaneous observation of item-level price and expenditure—yields improved measures of the cost of living. Accounting for ubiquitous quality change and for consumer substitution yields lower measures of inflation than traditional, official methods. (JEL C43, C45, E31, L15, L81)

商品级交易数据可产生能考虑质量变化和消费者替代的生活成本指数。交易数据需要应对商品的快速更替，因为新产品和现有产品的价格在均衡中相互关联。本文评估了多种大规模质量变化的测量方法。研究表明，特征超指数法——使用计量经济学或机器学习进行特征估计，结合需要同时观测商品级价格和支出的指数公式——能产生更优的生活成本衡量指标。考虑普遍的质量变化和消费者替代后，所得通胀指标低于传统的官方方法。

Conflict along transportation routes during Somalia’s al-Shabaab insurgency significantly increases maize prices at distant locations, decreasing food security, health, and education. Estimated conflict risk has strong price effects independently of realized conflict, highlighting the importance of safety concerns. A model of least-cost route choice in the presence of conflict reveals that more and shorter alternative routes to circumvent conflict can lower prices but their effectiveness diminishes as violence becomes more correlated across routes. Alternatively, securing key transportation routes would alleviate price increases. A market access approach suggests spatial spillovers of conflict also matter for prices of more general baskets of food and nonfood items. (JEL D74, I15, I25, O15, O17, Q11, R41)

在索马里青年党叛乱期间，沿交通路线的冲突显著提高了偏远地区的玉米价格，降低了粮食安全、健康和教育的可及性。估计的冲突风险即使在实际冲突未发生时也对价格有强烈影响，凸显了安全顾虑的重要性。一个考虑冲突存在下的最低成本路线选择模型表明，更多且更短的绕行替代路线可以降低价格，但其效果随着暴力在不同路线间变得更加相关而减弱。确保关键交通路线的安全将缓解价格上涨。市场准入方法表明，冲突的空间溢出效应也会影响更广泛的食品和非食品篮子的价格。

This paper develops an asset market-based test for preference for the timing of resolution of uncertainty. Our main theorem provides a characterization of preference for early resolution of uncertainty in terms of the risk premium realized during the period when the informativeness of macroeconomic announcements is resolved. Empirically, we find support for preference for early resolution of uncertainty based on evidence on the dynamics of the implied volatility of S&P 500 index options before Federal Open Market Committee announcements. (JEL D81, D83, G13, G14, G41)

本文提出了一种基于资产市场的检验方法，用于识别对不确定性解决时机的偏好。我们的主要定理从宏观经济公告信息含量解析期间实现的风险溢价角度，刻画了对早期不确定性解决的偏好。实证方面，基于标普 500 指数期权隐含波动率在联邦公开市场委员会（FOMC）公告前后的动态变化证据，我们找到了支持对早期不确定性解决偏好的证据。