1、收入不平等与最低工资:来自巴西的证据

提高最低工资可以显著减少收入不平等。为证明这一点，我们将行政数据和调查数据与巴西劳动力市场的均衡模型结合起来。我们发现，在1996年至2018年期间，巴西实际最低工资上涨了128%，这对收入分配中更高阶层的工资产生了深远的溢出效应。在此期间，收入不平等程度大幅下降，提高的最低工资贡献了其中的45%。与此同时，随着工人被重新分配到生产效率更高的企业，最低工资对就业和产出的影响会减弱。

Increases in the minimum wage can substantially reduce earnings inequality. To demonstrate this, we combine administrative and survey data with an equilibrium model of the Brazilian labor market. We find that a 128 percent increase in the real minimum wage in Brazil between 1996 and 2018 had far-reaching spillover effects on wages higher up in the distribution. The increased minimum wage accounts for 45 percent of a large fall in earnings inequality over this period. At the same time, the effects of the minimum wage on employment and output are muted by reallocation of workers toward more productive firms.

参考文献：Engbom, N., & Moser, C. (2022). Earnings inequality and the minimum wage: Evidence from Brazil. American Economic Review, 112(12), 3803-47.

2、互动、刻板印象和表现:来自南非的证据

我们利用南非一所大型大学对室友的随机分配来调查跨种族互动是否会影响刻板印象、个体态度和个体表现。使用隐性的关联测试，我们发现与不同种族的室友生活可以减少白人学生对黑人学生的负面刻板印象，并增加种族间的友谊。互动也会影响学习成果：黑人学生提高了GPA，通过了更多的考试，辍学率更低。这种效应不是由室友的能力驱动的。

We exploit a policy designed to randomly allocate roommates in a large South African university to investigate whether interracial interaction affects stereotypes, attitudes and performance. Using implicit association tests, we find that living with a roommate of a different race reduces White students' negative stereotypes towards Black students and increases interracial friendships. Interaction also affects academic outcomes: Black students improve their GPA, pass more exams and have lower dropout rates. This effect is not driven by roommate's ability.

参考文献：Corno, L., La Ferrara, E., & Burns, J. (2022). Interaction, stereotypes, and performance: Evidence from South Africa. American Economic Review, 112(12), 3848-75.

3、重载等待列表中的动态匹配

本文引入了一个程式化的模型来刻画等待列表的分配机制中的独特特征。首先，代理人在具有不同预期等待时间的项目中进行选择。等待时间在决定代理人的选择和配给物品方面起着与货币价格类似的作用。其次，项目的预期等待时间是内生决定的，并随时间随机波动。我们在这些内生决定的等待时间下评估福利，并发现了等待时间的波动会导致分配不当和福利损失。简单的随机分配策略则可以减少分配不当，提高福利。

This paper introduces a stylized model to capture distinctive features of waiting list allocation mechanisms. First, agents choose among items with associated expected wait times. Waiting times serve a similar role to that of monetary prices in directing agents' choices and rationing items. Second, the expected wait for an item is endogenously determined and randomly fluctuates over time. We evaluate welfare under these endogenously determined waiting times and find that waiting time fluctuations lead to misallocation and welfare loss. A simple randomized assignment policy can reduce misallocation and increase welfare.

参考文献：Leshno, J. D. (2022). Dynamic matching in overloaded waiting lists. American Economic Review, 112(12), 3876-3910.

4、随机对照试验配对设计的最优性

在随机对照试验中，实验组通常是分层随机分配的。我证明，在所有以1 / 2概率处理所有单元的分层随机化方案中，部分配对设计在估计平均处理效果方面达到了最大的统计精度。在某一重要的特殊情况下，优化设计还会根据基线结果对单元进行配对。而在基于10个随机对照试验数据集的模拟研究中，与原始设计相比，该设计将平均治疗效果估计器的标准误差平均降低了10%，且最高可降低34%。

In randomized controlled trials, treatment is often assigned by stratified randomization. I show that among all stratified randomization schemes that treat all units with probability one half, a certain matched-pair design achieves the maximum statistical precision for estimating the average treatment effect. In an important special case, the optimal design pairs units according to the baseline outcome. In a simulation study based on datasets from ten randomized controlled trials, this design lowers the standard error for the estimator of the average treatment effect by 10 percent on average, and by up to 34 percent, relative to the original designs.

参考文献：Bai, Y. (2022). Optimality of matched-pair designs in randomized controlled trials. American Economic Review, 112(12), 3911-40.

5、凸供给曲线

我们提供的证据表明，行业的供给曲线是凸的。为了明晰我们的实证分析，我们构建了一个模型，在该模型中，企业层面的能力约束导致了行业层面的对数凸供给曲线。该行业的产能利用率可以作为供给弹性的充分统计数据。利用产能利用率数据和三种不同的工具，我们估计了供给曲线，并找到了可以在经济意义上相当大的关于凸度的有力证据。我们确定的非线性具有一些宏观经济含义，包括对冲击的响应是依赖于状态的，以及菲利普斯曲线是凸的。

We provide evidence that industries' supply curves are convex. To guide our empirical analysis, we develop a model in which capacity constraints at the firm level generate supply curves that are convex in logs at the industry level. The industry's capacity utilization rate is a sufficient statistic for the supply elasticity. Using data on capacity utilization and three different instruments, we estimate the supply curve and find robust evidence for an economically sizable degree of convexity. The nonlinearity we identify has several macroeconomic implications, including that responses to shocks are state dependent and that the Phillips curve is convex.

参考文献：Boehm, C. E., & Pandalai-Nayar, N. (2022). Convex supply curves. American Economic Review, 112(12), 3941-69.

6、太阳黑子的交易

在一个具有多个帕累托排序均衡的模型中，我们表明，如果我们允许将太阳黑子的实现作为均衡选择方式的资产进行交易时，均衡集将缩小。当出现低产出结果的概率很高时，为防范这种情况，穷人承诺向高产出状态下的富人转移大笔资金。于是，富人就失去了付出维持高产出所需努力的动力。因此，金融市场的开放可能会破坏这种高度均衡。

In a model with multiple Pareto-ranked equilibria, we show that the set of equilibria shrinks if we allow trade in assets that pay based on the realization of a sunspot acting as an equilibrium-selection device. When the probability of a low-output outcome is high, the desire to insure against it leads the poor to promise large transfers to the rich in the high-output state. The rich then lose the incentive to exert the effort needed to sustain the high output. Thus the opening of financial markets may destroy the high equilibrium.

参考文献：Jovanovic, B., & Tsyrennikov, V. (2022). Trading on sunspots. American Economic Review, 112(12), 3970-94.

7、从可操纵的信号中学习

本文研究了委托人与代理人之间的动态停止博弈问题。委托人逐渐从具有噪音的表现中了解到代理人的私有类型，代理人则可以通过代价高昂的隐藏操作来操纵这些行为表现。我们充分刻画了这个博弈唯一的马尔可夫均衡。我们发现，在终止交易/市场崩溃之前，通常会出现操纵强度和(预期)表现的飙升。此外，由于内源性信号的操纵，过多的透明度会抑制学习，并损害委托人。当玩家变得非常有耐心时，委托人无法从观察到的信号中得到有用的信息。

We study a dynamic stopping game between a principal and an agent. The principal gradually learns about the agent's private type from a noisy performance measure that can be manipulated by the agent via a costly and hidden action. We fully characterize the unique Markov equilibrium of this game. We find that terminations/market crashes are often preceded by a spike in manipulation intensity and (expected) performance. Moreover, due to endogenous signal manipulation, too much transparency can inhibit learning and harm the principal. As the players get arbitrarily patient, the principal elicits no useful information from the observed signal.

参考文献：Ekmekci, M., Gorno, L., Maestri, L., Sun, J., & Wei, D. (2022). Learning from manipulable signals. American Economic Review, 112(12), 3995-4040.

8、动态特赦计划

监管者面对的是一系列从事具有随机回报犯罪行为的代理人。监管机构设计了一项大赦计划，承诺对举报犯罪的罪犯实施时间性惩罚。在最优方案中，犯罪收益的时间变化会导致特赦慷慨度的时间变化。我构造了一个最优时间路径，并由此得出了赦免周期。随着时间的推移，大赦会越来越慷慨，直到达到一个界限，之后循环重置。从事高回报犯罪的代理人在每个周期结束时举报，而从事低回报犯罪的代理人始终举报。

A regulator faces a stream of agents engaged in crimes with stochastic returns. The regulator designs an amnesty program, committing to a time path of punishments for criminals who report their crimes. In an optimal program, time variation in the returns from crime can generate time variation in the generosity of amnesty. I construct an optimal time path and show that it exhibits amnesty cycles. Amnesty becomes increasingly generous over time until it hits a bound, after which the cycle resets. Agents engaged in high return crime report at the end of each cycle, while agents engaged in low return crime report always.

参考文献：Kapon, S. (2022). Dynamic amnesty programs. American Economic Review, 112(12), 4041-75.

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