Topics in the Economic Theory of Networks

该项目推进了网络经济理论。许多其他学科的研究都证明了网络对经济活动的重要性。然而，经济学家才刚刚开始发展网络相互作用的理论。这项研究将为经济学家提供一种思考谁与谁做生意以及为什么做生意的新方法。因此，它有望改变经济理论和政策。该提案的第一部分建立了一个工业网络模型，其中几个制造商与几个供应商打交道，反之亦然。该项目重新审视了一个核心政策问题和理论难题——垂直合并如何影响经济福利？长期以来，理论家和监管者都认为，两家公司的垂直合并可以带来更好的内部协调和投资。该项目通过考虑合并对所有投资的影响，而不仅仅是合并的内部投资，挑战了这种见解。该项目表明，公司可以在这些投资中进行战略竞争，并展示了合并后的公司如何操纵其投资以增加其利润，但对其他公司来说是亏损的。研究结果将改变理论家看待产业竞争的方式，并为政策制定者如何评估垂直并购提供信息。这个项目的第二部分研究社交网络和对新技术和信息的搜索。许多研究认为，沟通和向他人学习对经济活动和创新很重要。例如，在购买新产品或投资新技术之前，人们会询问朋友、邻居和同事的体验。项目对这个过程进行建模。它引入了一种新的模式，即个人进行实验，然后将结果与朋友和同事交流。该项目提出的问题是：通信链接的模式如何决定搜索和实验的模式？人们是自己搜索还是依赖别人？新的联系——例如社区或公司之间的联系——如何影响实验、搜索模式和福利？这些问题的答案应该改变人们设计制度和政策的方式，以增加经济和社会不同部分之间的沟通。

This project advances the economic theory of networks. Research in many other disciplines documents the importance of networks for economic activity. Yet, economists have only begun to develop theories of network interactions. This research will provide economists a new way of thinking about who does business with whom and why. It thus promises to change both economic theory and policy. The first part of the proposal builds a network model of industry, where several manufacturers deal with several suppliers, and vice versa. The project takes a new look at a central policy question and theoretical puzzle -- how do vertical mergers affect economic welfare? It has long been argued - by both theorists and regulators - that vertical merger of two firms can lead to better internal coordination and investments. The project challenges this insight by considering the impact of merger on all investments, not just those internal to the merger. The project shows firms can strategically compete in these investment and demonstrates how a merged firm can manipulate its investments to increase its profits, but at a loss to other firms. The results should change the way theorists view industrial competition and inform how policy makers evaluate vertical mergers. The second part of this project studies social networks and the search for new technologies and information. Many studies have argued that communication and learning from others is important for economic activity and innovation. For example, before purchasing a new product or investing in a new technology, people inquire into the experiences of friends, neighbors, and colleagues. The project models this process. It introduces a new model where individuals experiment, then communicate their results to friends and colleagues. The project asks: how does the pattern of communication links determine the pattern of search and experimentation? Do people search themselves or rely on others? How do new links - links between communities or firms, for example - affect experimentation, search patterns and welfare? The answers to these questions should change the way people design institutions and policies to increase communication between different parts of the economy and society.