Price Discrimination and Competition in Many-to-Many Matching Markets

本项目开发了一个新的理论框架，用于研究多对多匹配市场，即平台企业销售的产品可以进入其他代理商的市场。研究小组首先调查了平台如何进行二级价格歧视，将代理商分类到多个（可能是非排他性的）网络中。尽管这些做法在提供保健、有线电视、互联网服务和在线广告等多对多匹配市场中很常见，但对这些做法的理论分析是有限的。他们使用一种机制设计方法。这使他们能够阐明平台的利润最大化实践和他们所诱导的分配，而不会对网络架构（例如，单归巢）和定价策略（例如，两部分关税）施加特别限制。分析的出发点是认识到这样一个事实，即此类市场中的代理商通常拥有私人信息，既包括他们为接触其他代理商而付费的意愿，也包括决定他们对匹配代理商吸引力的特殊特征。例如，在医疗保健竞争中，患者拥有私人信息，既包括他们是否愿意付费加入不同的医生网络，也包括各种特殊特征（健康状况、生活方式、风险），这些信息决定了医生期望从这些患者加入网络中获得的利润。分析揭示了(i)与私人和公共提供匹配服务相关的扭曲，（ii）这种扭曲如何取决于平台竞争的程度，（iii）政府如何通过使用补贴和税收等工具纠正这种低效率来增加福利（在某些情况下，施加普遍服务义务），以及（iv）在私人和公共提供下更有可能出现什么样的网络结构(例如，(v)改变估值分布和/或双方吸引力的各种冲击对利润、网络结构和福利的影响。该团队还研究了信息分散如何影响双边市场中的均衡价格和网络分配，在双边市场中，多个平台相互竞争以吸引每一方的用户。研究人员开发了一个模型，在这个模型中，代理人被允许对竞争平台的服务有水平差异化的偏好，以及关于他们加入平台的效用和关于偏好和信息在人口横截面中的分布的私人信息。这种丰富性旨在揭示由于网络外部性而在双边市场中出现的熟悉效应如何与来自信息分散的新颖（和未探索的）效应相互作用。该分析使用了“全球博弈”文献中的技术，以获得均衡唯一性的便利性，同时允许这种均衡的结果依赖于竞争平台的内生定价策略。理解信息的分散在这样的市场中扮演的角色是有帮助的，例如，理解平台的广告活动对网络结构、利润、消费者剩余和福利的影响。所提议的活动预计将与对匹配问题感兴趣的经济理论的各个分支（双边市场、卫生保健经济学、学校分配问题、网络经济学）相关，也与这些市场中的从业者相关，他们可以将理论分析用于实验和实证工作。其结果将有助于制定竞争政策、促进采用新技术的政策和保健政策。

This project develops a new theoretical framework for studying many-to-many matching markets, that is, markets where the product sold by a platform firm is access to other agents. The research team first investigates how platforms can engage in second-degree price discrimination to sort agents into multiple (possibly non-exclusive) networks. Despite the fact that these practices are common in many-to-many matching markets such as the provision of health care, cable TV, internet services, and online advertising, the theoretical analysis of such practices is limited. They use a mechanism design approach. This allows them to shed light on the platforms' profit-maximizing practices and on the allocations that they induce, without imposing ad-hoc restrictions on the network architecture (e.g., single-homing) and on the pricing strategies (e.g., two-part tariffs). The starting point of the analysis is the recognition of the fact that agents in such markets typically have private information both about their willingness to pay to reach other agents as well as about idiosyncratic characteristics that determine their attractiveness for those agents they are matched to. For example, in the contest of health care, patients have private information both about their willingness to pay to join different physician networks, as well as about various idiosyncratic characteristics (health status, life style, risks) that determine the profits that the physicians expect from having such patients in the network. The analysis sheds light on (i) the distortions associated with the private and public provision of matching services, (ii) how such distortions depend on the degree of platform competition, (iii) how the government can increase welfare by correcting such inefficiencies using instruments such as subsidies and taxes (and, in some cases, imposing universal service obligations), but also (iv) what network structures are more likely to emerge under private and public provision (e.g., single-homing vs multi-homing), (v) the effects on profits, network structure, and welfare of various shocks that alter the distribution of valuations and/or the attractiveness of the two sides. The team also studies how the dispersion of information affects the equilibrium prices and the network allocations in two-sided markets where multiple platforms compete to attract users on each side. The researchers develop a model where agents are allowed to have horizontally differentiated preferences for the services of the competing platforms as well as private information both about their utility from joining the platforms and about the distribution of preferences and information in the cross-section of the population. This richness is meant to shed light on how the familiar effects that emerge in two-sided markets due to network externalities interact with the novel (and unexplored) effects coming from the dispersion of information. The analysis uses techniques from the literature on "global games" to obtain the convenience of equilibrium uniqueness while at the same time permitting the outcome of such equilibrium to depend on the endogenous pricing strategies of the competing platforms. Understanding the role that the dispersion of information plays in such markets is instrumental, for example, to understanding the effects of platforms' advertising campaigns on network structure, profits, consumer surplus, and welfare. The proposed activity is expected to be relevant both for the various branches of economic theory interested in matching problems (two-sided markets, health care economics, school assignment problem, network economics), but also for practitioners in such markets who can use the theoretical analysis for experimental and empirical work. The results will be useful for competition policy, policy to promote the adoption of new technologies, and health care policy.