Author: Adrien Vigier
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Category :
Languages : en
Pages :

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Author: Won Hee Park
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Category :
Languages : en
Pages :

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This dissertation consists of two projects, both concerned with how social networks form and how they affect economic decisions. In the first project, entitled Identifying Influential Agents in a Social Network, I define influence centrality, a new measure of influence which combines information on node and neighbor characteristics as well as information on the network structure, by building a model of friendship formation and peer effects and calculating the change in the equilibrium behavior of the network when one node changes its behavior. I apply the model to the context of smoking among middle and high school students and show that a targeted anti-smoking intervention in which a small number of influential smoking students are treated may be more efficient than a uniform program where every student in the school receives the same anti-smoking treatment. The second project, entitled Quantifying Spillovers in Network Formation Over Time, is a joint work with Sean Chu and Shankar Kalyanaraman at Facebook. The goal of the project is to separately identify and understand the relative importance of network effects and unobserved heterogeneity in a multi-period network formation model. Here, we define network effects to be the effect of the number of mutual friends on the probability of friendship and assume that unobserved heterogeneity is time-consistent. We estimate the model on a de-identified panel data set from a small group of users on Facebook and find that both network effects and unobserved heterogeneity are statistically and economically significant predictors of friendship formation on Facebook. We further re-estimate the model first, without network effects and next, without unobserved heterogeneity. Comparing the results from these specifications, we find that network effects play a more important role than unobserved heterogeneity in network formation models on Facebook.

Author: Wang Xiang
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Category :
Languages : en
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In this dissertation, I provide three social network models addressing different aspects of the economy.First, I consider the issue of social network formation. Meeting with strangers and meeting with friends friends are two common patterns when observing the formation of social networks and thus are widely adopted in many statistical network formation settings. I establish a network formation model trying to find the individual level incentive behind the two patterns. Each agent enters the network sequentially choosingbetween forming global random links or connecting with friends' friends, knowing that his payoff depends on the distance between the player with valuable information and himself. I find that the distance between players in the resulting network asymptotically follows a Weibull distribution and the link formation decision depends on how easily information can be transmitted under the network. When the transmission is relatively easy and information can be received from far away, players prefer to meet with strangers. Otherwise they prefer to connect with friends friends. The second model considers a moral hazard scenario in which a monitor must detect deviations so as to provide proper incentives to attain an efficient outcome. What if the monitor himself were to deviate after being bribed by his monitored subject? I explore a multi-agent public-good provision game in which each player prefers shirking to working in the absence of exogenous enforcement and can bribe those assigned to monitor him. I find that when players agree to cooperate in choosing an optimally designed monitoringnetwork, a core-periphery monitoring network results, with a small group of heavily monitored players who monitor all others. Under this network, a perfect Bayesian equilibrium (PBE) is supported in which shirking is prevented, bribing among players ceases and total monitoring costs are minimized. Further, the efficiency of this core-periphery structure is robust under various settings, including the dynamic spread of bribing, and under different punishments and monitoring schedules.Lastly, I consider a phenomenon of innovation adoption and diffusion. Innovations are crucial to the long run economic growth; however, not all new ideas are adopted by the majority of the society even though similar ones which appear later turn out to be commercial successes. I establish a model in which multiple potential entrants each can bring a new technology into a market with consumers connected under a social network.Technology has the character of network externality and entrants must rely on the word-of-mouth communication under the social network to promote their products. I find that high quality innovations are not guaranteed to perform better than low quality ones under the scenario and timing is a crucial determinant of their commercial performances. Low quality innovation firms are likely to enter the market whenever possible but high quality ones might strategically wait for a proper time to acquire a better market share.

Author: Wei Cheng (Ph. D. in economics)
Publisher:
ISBN:
Category : Economics
Languages : en
Pages : 117

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The third essay studies the productivity spillovers from colleagues and coauthors simultaneously for scientific workers. I use department fixed effects and individual fixed effects to control for departmental common shocks and individual selection. In addition, I model scientists’ mobility choices and use citation breakout as the exclusion variable to address the potential endogenous year-to-year change in colleague networks. Having solved the endogeneity issue of colleague networks, I construct instruments for coauthor quality by exploiting the characteristics of the (estimated staying) colleagues of a scientist’s noncolleague coauthors. Our results provide strong evidence coauthors generate significant spillover effects while colleagues do not. Increasing the number of a scientist’s coauthors by one on average increases his productivity by 2%. Our findings highlight the important of being exposed to a wider spectrum of ideas and knowledge in the production of science. Additionally, spillovers from colleagues remain insignificant across departments of different sizes or quality, and the estimated magnitude of coauthor spillovers is robust to different specifications and subsamples.

Author: Livia Shkoza
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Isabel Melguizo López
Publisher:
ISBN: 9788449064616
Category :
Languages : en
Pages : 402

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Los individuos a menudo exhiben robustos patrones de comportamiento al relacionarse con otros y cuando toman decisiones económicas. Por ejemplo, tienden a interactuar de manera desproporcionada con otros similares a ellos. Además, las dimensiones no-cognitivas de la personalidad, como la confianza o la perseverancia afectan a la dilación de las tareas. Esta tesis incorpora estos patrones de comportamiento en modelos económicos de aprendizaje social y de decisiones sobre el momento en el que desarrollar tareas. En el primer capítulo argumentamos cómo los desacuerdos se pueden perpetuar en la sociedad cuando los individuos forman sus opiniones comunicándose de manera desproporcionada con sus similares. Para ello consideramos un modelo dinámico de formación de opinión en el que los individuos desarrollan sus opiniones mediante la incorporación de las de otros en su red social. Nuestros individuos exhiben homofilia, esto es, la atención que prestan a otros se basa en la posesión de atributos similares. La característica clave de este marco es que la atención co-evoluciona con las opiniones, regida por cuán sobresalientes son los atributos. Esta prominencia viene dada por la diferencia de opiniones entre los grupos que poseen y que carecen de estos atributos. Al asumir que los atributos con mayores diferencias en opiniones merecen más atención, mostramos si hay, inicialmente, un único atributo sobresaliente, éste recibe una atención creciente en el tiempo y la sociedad queda escindida en dos grupos de pensamiento. Esta situación se presenta porque los individuos reorientan sus interacciones con otros similares en el rasgo más saliente de tal manera que las opiniones no se mezclan. En el segundo capítulo complementamos el estudio del primero explorando cómo modificaciones en el comportamiento de los individuos afectan a la formación de opiniones. Incorporamos el caso en el cual las opiniones están sujetas a las perturbaciones y demostramos que el desacuerdo es robusto a la aleatoriedad. También discutimos el caso en que los individuos se influencian entre sí con diferentes intensidades, como McPherson et al. (2001) documenta, los jóvenes exhiben mayor homofilia de género que los mayores. Encontramos que cuando algunos individuos agravan la atención que prestan al rasgo más sobresaliente inicialmente, el desacuerdo persiste a través de él, siendo las diferencias en opiniones más mayores que en el caso simétrico. Finalmente exploramos condiciones generales sobre la evolución de la homofilia para que el desacuerdo persista. En el primer capítulo discutimos un proceso particular en el que la evolución de homofilia promueve el desacuerdo, por el contrario, la homofilia constante en Golub y Jackson (2012) afecta a la velocidad de convergencia al consenso, un resultado que siempre surgía. La conciliación de ambos resultado descansa en afirmar que el desacuerdo persiste siempre que que los individuos intensifiquen sus relaciones con otros similares, suficientemente rápido. Específicamente, hay dos fuerzas en juego: primero, las personas prestan cada vez más atención a los demás sobre la base de un atributo específico. Segundo, siempre prestan atención a todos los demás. El desacuerdo persiste cuando la primera domina. En el último capítulo, discutimos la relevancia de las habilidades no-cognitivas en la decisión de cuándo hacer frente a tareas difíciles, pero valiosas. Para ello consideramos un marco dinámico con un individuo caracterizado por el potencial con el que ejecuta sus habilidades. Mostramos que cuando este individuo presenta bajo potencial, se enfrenta siempre a tareas fáciles de bajo valor mientras que cuando presenta alto potencial, se enfrenta siempre a tareas difíciles. Cuando este potencial es sensible a la consecución de resultados, el individuo puede encontrar óptimo pasar de tareas fáciles a difíciles en algún momento. Intuitivamente, los éxitos en tareas fáciles lo motivan a enfrentarse a tareas difíciles.

Author: Javier Mejía Cubillos
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Category :
Languages : en
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"This dissertation intends to open the discussion on 1- How did non-market interactions shape the economy in the long-term? 2- How did economic activity shape non-market interactions in the long-term? Three papers compose the dissertation. Paper 1: The Network Formation Origin of Tribal Societies. Paper 2: Social Interactions and Modern Economic Growth. Paper 3 (JMP): Social Networks and Entrepreneurship. Evidence from a Historical Episode of Industrialization." -- Tomado del Formato de Documento de Grado.

Author: Arun Gautham Chandrasekhar
Publisher:
ISBN:
Category :
Languages : en
Pages : 210

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(cont.) substitutes for commitment. On net, savings allows individuals to smooth risk that cannot be shared interpersonally, with the largest benefits for those who are weakly connected in the network. The final chapter (co-authored with my classmates Horacio Larreguy and Juan Pablo Xandri) attempts to determine which models of social learning on networks best describe empirical behavior. Theory has focused on two leading models of social learning on networks: Bayesian and DeGroot rules of thumb learning. These models can yield greatly divergent behavior; individuals employing rules of thumb often double-count information and may not exhibit convergent behavior in the long run. By conducting a unique lab experiment in rural Karnataka, India, set up to exactly differentiate between these two models, we test which model best describes social learning processes on networks. We study experiments in which seven individuals are placed into a network, each with full knowledge of its structure. The participants attempt to learn the underlying (binary) state of the world. Individuals receive independent, identically distributed signals about the state in the first period only; thereafter, individuals make guesses about the underlying state of the world and these guesses are transmitted to their neighbors at the beginning of the following round. We consider various environments including incomplete information Bayesian models and provide evidence that individuals are best described by DeGroot models wherein they either take simple majority of opinions in their neighborhood.

Author: Nazmun Nahar Ratna
Publisher:
ISBN:
Category : Communication in economic development
Languages : en
Pages : 202

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Author: Vania Bitia Salas García
Publisher:
ISBN:
Category :
Languages : en
Pages : 166

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