This dissertation consists of three essays studying human behavior and contagion phenomenon in networks. The analysis especially focuses on information sharing, trade relationship and pest spread in networks. The first chapter outlines the dissertation by briefly discussing the motivations, methods, and main findings in each of the following chapters.
Chapter two examines the information sharing in networks. We develop a heterogenous agents model in which connections between players act as a channel to exchange information. We focus on specialized equilibria, which is based on Nash tatonnement. It is shown that players utilize the signals in the linear form and only specialized equilibria can be stable. We also compare the sequential equilibria and stable equilibria, and it is shown that stable equilibria form a proper subset of the sequential ones, which gives a sharper prediction. The stable equilibria demonstrate star-like graphs, which is similar to the phenomenon "the law of the few" in the literature.
Chapter three investigates the trade relationship among players where trade between two players can bring benefits as well as conflict. And if conflict happens, the players coordinate based on received information. We show that the optimal structure of trade networks ranges from complete market to Autarky. Also, we study the optimal timing for trade relationship establishment and the optimal size of organizations when facing scarce members. It is shown that when potential neighbors become more scarce, people care more about the future, or new technology breakthroughs occur more frequently, it is optimal to have more neighbors to back up for the potential technological breakthrough.
The last chapter studies the pest spread in the networks. We use a directional and weighted network to study the spread of Tuta absoluta. A robust network-based approach is proposed to model seasonal flow of agricultural produce and examine its role in pest spread. Furthermore, the long-term establishment potential of the pest and its economic impact on the country are assessed. Preliminary analyses indicate that Tuta absoluta will invade most major tomato production regions within a year of introduction and the economic impact of invasion could range from $17-25 million. / Ph. D. / Networks play an important role in the society today, for example, the Internet, Facebook and other social media, cell phones, and communication networks. Networks have undeniable effects on human activity in modern society and this dissertation will focus on three topics: information sharing in networks, trade networks and diffusion in the networks.
Information sharing in networks: In the society, individuals have different ability to refine signals, so their strategy about information will be different. In this paper, we assume that there are noisy signals about the true state of the world and individuals have a tradeoff between refining their signals by themselves and connecting to others to receive information. It is shown that players utilize the signals in the linear form and only specialized equilibria can be stable. Furthermore, the stable equilibria demonstrate star-like graphs, which is similar to the phenomenon “the law of the few” in the literature.
The structure of trade networks: Trade is ubiquitous in modern society and has undeniable effects on human activity. The trade relationship among players can bring benefits as well as conflict. Facing the advantages and disadvantages of trade, players need to make decisions about who to trade with. We show that the optimal structure of trade networks ranges from complete market to Autarky as economy environment changes. Also, we study the optimal timing for trade relationship establishment and the optimal size of organizations when facing scarce members. It is shown that when potential neighbors become more scarce, people care more about the future, or new technology breakthroughs occur more frequently, it is optimal to have more neighbors to back up for the potential technological breakthrough.
Diffusion in networks: Diffusions like information, diseases, rumor are usually through the network in the society. We study the pest spread Nepal in the networks. Based on road networks and trade patterns, we model the flow networks of the pest spread. Based on the flow network, the long-term establishment potential of the pest and its economic impact on the country are assessed. Preliminary analyses indicate that Tuta absoluta will invade most major tomato production regions within a year of introduction and the economic impact of invasion could range from $17-25 million.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/96195 |
| Date | 29 June 2018 |
| Creators | Shi, Bowen |
| Contributors | Economics, Sarangi, Sudipta, Haller, Hans H., Bravard, Christophe, Ball, Sheryl B., Tsang, Kwok Ping, Bahel, Eric A. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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