唧唧堂：JPE政治经济学期刊2021年02月刊论文摘要翻译

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1、闲暇奢侈品和年轻人的劳动供给

我们提出了一种方法，通过挖掘时间数据和闲暇时间的恩格尔曲线来推断闲暇活动的质量改变，并测量质量改变对闲暇的边际收益率的影响。我们研究了21岁到30岁之间的男性的闲暇时间收益，这些男性从2004年起将闲暇时间转向了视频游戏和娱乐计算领域，并且相比更年长男性和女性减少了更多的工作时间。我们发现娱乐计算对年轻男性来说显然是一种闲暇消费奢侈品。通过增加时间的价值，这种闲暇技术的革新使得年轻男性工作时间减少了2%，或者说相比更年长男性，工作时间减少了2%。

摘要原文：We propose a methodology exploiting time diary data and “leisure Engel curves” to infer quality changes across leisure activities and measure the effects on the marginal return to leisure. We study leisure returns for men aged 21–30, who have shifted leisure toward video gaming and recreational computing and have had larger market work hour declines than older men or women since 2004. We show that recreational computing is distinctly a leisure luxury for younger men. By increasing the value of time, innovations to this leisure technology have lowered young men's work hours by 2%, or much of their work hours decline compared to older men's.

参考文献：Mark Aguiar, Mark Bils, Kerwin Kofi Charles, and Erik Hurst (2021). Leisure Luxuries and the Labor Supply of Young Men. Journal of Political Economics, 129(02)：337–382.

2、动态锦标赛设计：来自预测比赛的经验

在线比赛已经变成创新采购的一种重要形式。比赛平台经常展示出一个实时的公共排行榜来提供成绩反馈。对玩家决策进行信息披露的影响在理论上是不确定的。一些玩家可能会觉得沮丧然后退出，另一些则可能决定继续努力来保持竞争力。我们采用两种互补的方法调查了排行榜对比赛结果的影响。首先，我们用观察数据估测了一个动态模型，并比较了有无排行榜的均衡。其次，我们展示了从学生比赛中得到的实验证据。我们发现平均而言排行榜改善了比赛结果。

摘要原文：Online contests have become a prominent form of innovation procurement. Contest platforms often display a real-time public leaderboard to provide performance feedback. The impact of information disclosure on players’ decisions is theoretically ambiguous: some players may get discouraged and quit, while others may decide to keep working to remain competitive. We investigate the impact of a leaderboard on contest outcomes using two complementary approaches. First, we estimate a dynamic model using observational data and compare the equilibria with and without a leaderboard. Second, we present experimental evidence from student competitions. We find that a leaderboard on average improves competition outcomes.

参考文献：Jorge Lemus and Guillermo Marshall (2021). Dynamic Tournament Design: Evidence from Prediction Contests. Journal of Political Economics, 129(02)：383–420.

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3、多产品中介

这篇文章建立了一个新的框架，来研究消费者具有多产品需求并面对着搜索摩擦时的多产品中介。我们发现即使是在并没有改善消费者搜索效率的情况下，多产品中介也是盈利的。中介独家存储高价值产品来吸引顾客拜访，然后通过卖出那些从上游供应商处可以较便宜买到的非独家经营产品来获利。跟社会最优结果相比，中介显得太过庞大，并且独家储存了过多的产品。我们使用这个框架来研究购物商场的设计和在零售市场上上游供应商对消费者的直接销售的影响。

摘要原文：This paper develops a new framework for studying multiproduct intermediaries when consumers demand multiple products and face search frictions. We show that a multiproduct intermediary is profitable even when it does not improve consumer search efficiency. The intermediary optimally stocks high-value products exclusively to attract consumers to visit and then profits by selling nonexclusive products that are relatively cheap to buy from upstream suppliers. Relative to the social optimum, the intermediary tends to be too big and stock too many products exclusively. We use the framework to study the design of shopping malls and the impact of direct-to-consumer sales by upstream suppliers on the retail market.

参考文献：Andrew Rhodes, Makoto Watanabe, and Jidong Zhou (2021). Multiproduct Intermediaries. Journal of Political Economics, 129(02)：421–464.

4、饮用水中氟化物的影响

饮用水加氟是一个常见但是受到争议的公共政策。在这篇文章里，我们使用瑞典记录保管处的数据来研究饮用水中氟化物的因果效应。我们利用自然氟化物的外源性变化来识别氟化物的效应,这些外源性变化源自于水源处的地理特征差异。首先，我们再次证实长期认可的氟化物对于牙齿健康的积极作用。第二，与近来一些争议的流行病学研究形成对比的是，我们估测氟化物对于认知能力的影响为零。第三，氟化物能进一步增加劳动收入。这个效应主要体现在具有较差社会经济背景的群体中。

摘要原文：Water fluoridation is a common but debated public policy. In this paper, we use Swedish registry data to study the causal effects of fluoride in drinking water. We exploit exogenous variation in natural fluoride stemming from variation in geological characteristics at water sources to identify its effects. First, we reconfirm the long-established positive effect of fluoride on dental health. Second, we estimate a zero effect on cognitive ability in contrast to several recent debated epidemiological studies. Third, fluoride is furthermore found to increase labor income. This effect is foremost driven by individuals from a lower socioeconomic background.

参考文献：Linuz Aggeborn and Mattias Öhman (2021). The Effects of Fluoride in Drinking Water. Journal of Political Economics, 129(02)：465–491.

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5、需求为基础的最优财务援助

我们将学生的财务援助作为家长收入的函数来研究最优的财务援助设计。我们从一个一般模型中得到了最优的财务援助公式。我们为美国估测了一个大学选择模型，这个模型包含了多维度的异质性、内生的家长转移支付、辍学、大学的劳动收入和不确定收入的情况。我们在估测模型里量化了最优的财务援助，发现即使在没有考虑分配的情况下它也会随着家长收入的上升而大幅下降。平等和公正并肩前行。

摘要原文：We study the optimal design of student financial aid as a function of parental income. We derive optimal financial aid formulas in a general model. We estimate a model of selection into college for the United States that comprises multidimensional heterogeneity, endogenous parental transfers, dropout, labor supply in college, and uncertain returns. We quantify optimal financial aid in the estimated model and find it is strongly declining in parental income even without distributional concerns. Equity and efficiency go hand in hand.

参考文献：Mark Colas,Sebastian Findeisen, and Dominik Sachs (2021). Optimal Need-Based Financial Aid. Journal of Political Economics, 129(02)：492–533.

6、初创企业和市场新贵：研发中的不利信息

我们研究了一个在老牌公司和初创企业之间进行的不对称信息下的研发竞赛。只有在创新是可行的情况下，研发投资才会随机地带来成功。研发竞赛中唯一的不对称是老牌公司对创新的可行性有更好的信息。我们发现会形成一种均衡，相比拥有更多信息的老牌公司，拥有更少信息的初创企业赢得竞赛的次数更多，也会有更高的预期利润。当信息不对称很大时，这是唯一的均衡结果。更好的信息获取变成竞争劣势的路径看上去非常新颖，源于更好的信息弱化了向竞争对手学习的激励。

摘要原文：We study an R&D race between an established firm and a startup under asymmetric information. R&D investment brings success stochastically, but only if the innovation is feasible. The only asymmetry is that the established firm has better information about the feasibility of the innovation. We show that there is an equilibrium in which the poorly informed startup wins more often, and has higher expected profits, than the better-informed incumbent. When the informational asymmetry is large, this is the unique equilibrium outcome. The channel by which better information becomes a competitive disadvantage appears to be new and stems from the fact that better information dulls the incentive to learn from one’s rival.

参考文献：Yu Awaya and Vijay Krishna (2021). Startups and Upstarts: Disadvantageous Information in R&D. Journal of Political Economics, 129(02)：534–569.

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7、健康保险竞争有作用吗？来自医疗保险优势项目的经验

我们预测了医疗优势项目在它改革后的竞标规则下创造的经济剩余。我们使用医疗保险受益人的经历数据，并建立了一个计划竞价的方案模型，这个模型同时考虑到了市场力量和风险选择。我们估测医疗保险优势项目给参与者创造了大量的剩余（每个入会者每月217美元），但是大概三分之二的剩余由保险公司获得。我们使用模型来评估可能的项目改变带来的影响，这些改变包括那些在不提高纳税人成本的情况下增加竞争从而减少利润并提高消费者剩余的改变。

摘要原文：We estimate the economic surplus created by the Medicare Advantage program under its reformed competitive bidding rules. We use data on the universe of Medicare beneficiaries and develop a model of plan bidding that accounts for both market power and risk selection. We estimate that the Medicare Advantage program generates substantial surplus to participants (of $217 per enrollee-month), but that approximately two-thirds of this surplus is captured by insurers. We use the model to evaluate the impact of possible program changes, including changes that could increase competition and lead to lower profits and higher consumer surplus without raising taxpayer costs.

参考文献：Vilsa Curto, Liran Einav, Jonathan Levin, and Jay Bhattacharya (2021). Can Health Insurance Competition Work? Evidence from Medicare Advantage. Journal of Political Economics, 129(02)：570–606.

8、执行指令和做笔记：在国债拍卖中的交易商信息共享

金融公司使用的指令流信息已经成为了监管讨论的重点话题。一个通过执行客户指令来获取信息的交易商应该被允许使用和分享这些信息吗？我们在一个根据拍卖结果数据修正过以量化反事实结果的模型中，探索了信息分享如何影响美国国债拍卖中的交易商、客户和发行者收益。信息分享降低了未来价值的不确定性。在更低的不确定性下，风险规避的出价者会出价更高。对投资者来说，信息分享的福利影响取决于信息是如何分享的以及它如何影响了不对称性。模型显示当交易商之间共享信息而不是交易商更多跟客户分享信息时，投资者可以获益。