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Technical proofs and robustness analysis

We consider a model of local public goods in a random network context. The influence network determines (exogenously) who observes whom every period and comprises a wide array of options depending on the degree distribution and the in/out-degree correlations. We show that there exists a unique equilibrium level of public good provision and compare it with the efficient level. We derive further insights for this problem by performing a comparative statics analysis.

We study a model where agents, located in a social network, decide whether to exert effort or not in experimenting with a new technology (or acquiring a new skill, innovating, etc.). We assume that agents have strong incentives to free ride on their neighbors' effort decisions. In the static version of the model efforts are chosen simultaneously. In equilibrium, agents exerting effort are never connected with each other and all other agents are connected with at least one agent exerting effort. We propose a mean-field dynamics in which agents choose in each period the best response to the last period's decisions of their neighbors. We characterize the equilibrium of such a dynamics and show how the pattern of free riders in the network depends on properties of the connectivity distribution.

Programa de Doctorado en Administración y Dirección de Empresas, Línea de Investigación: Métodos Cuantitativos para la Gestión, Clave Programa: DAE, Código Línea: 105, The tools chosen as the engine of the research, and the common thread of this thesis, will be experiments, economic experiments, where we infer agents behavior after observing their actions against different contexts, specifically we will update the traditional economic experiments in behavioral economics literature to adapt them to a more future-focused working methodology, In chapter 2 and 3 we will adapt the experiments to be conducted in an interconnected and experiential environment. In chapter 4, we will focus the experience on a teaching dynamic lessons plan where students will learn by playing with some of the main concepts of behavioral economics, breaking the classroom barrier and leaving the laboratories to a more relaxed environment. More specifically, a summary of these chapters would be: Does volunteering increase employment opportunities? We study the benefits of doing volunteer work when seeking employment opportunities. We do so by sending 2000 fictitious curricula to a large online platform of job offers in the United States. Half of these curricula are randomly assigned volunteer activities. We find that people who do volunteer work receive 45 percent more callbacks for interviews. The volunteering premium is not uniform across economic sectors. In retailing and real estate, it is significant, whereas in the other sectors we have studied (animal service, technology, and automobile) it is not. Does the die-under-the-cup device exaggerate cheating? Using a powered online experiment (774 subjects, 54\% female, av. age = 24.27) under the die-under-the-cup paradigm, this paper shows that a minimal variation (reversing payoffs) increases participants¿ honesty. Dice numbers and monetary prizes are aligned in the control treatment (1->5€, 2->10€, ¿, 6->30€), while numbers and monetary prizes go in opposite directions in the reversed treatment (1->30€, 2->25€, ¿, 6->5€). Although this small variation has no theoretical consequences, it results in more honest behavior. Since the participants in the control and the treatment are identical, we conclude that the observed dishonesty is caused by the task, that is, it is an artifact. The effect is stronger for women and older participants. Taking risks by flying paper airplanes. We propose an outdoor activity to be conducted in game theory courses where students are invited to throw airplanes at a distance of their choice in order to reach a certain target. The prize (class points) will increase as the distance students throw the airplane increases and it will be conditional on hitting the target. Subjects repeat the task three times and the best of the three determines their payoffs. The main purpose of these outdoor classroom experiments is to motivate students to learn by experiencing concepts of uncertainty in the gain domain (risk aversion). After the experiment, students are predisposed to think about decisions under uncertainty. Specifically, we provide a theoretical model to explain participants' decisions, optimal behavior, and deviations from such behavior., Universidad Pablo de Olavide de Sevilla. Departamento de Economía, Métodos Cuantitativos e Historia Económica

This Ph.D. dissertation develops theories of dynamic social influence. In a dynamic framework, individuals interact repeatedly with their social environment and exchange beliefs and opinions on various economic, political and social issues. In Chapter 2, we study influence processes modeled by ordered weighted averaging operators. These operators are anonymous: they only depend on how many agents share a belief. We find a necessary and sufficient condition for convergence to consensus and characterize outcomes where the society ends up polarized. Furthermore, we apply our results to fuzzy linguistic quantifiers. In Chapter 3, we introduce the possibility of manipulation into the model by DeGroot (1974). We show that manipulation can modify the trust structure and lead to a connected society. Manipulation fosters opinion leadership, but the manipulated agent may even gain influence on the long-run beliefs. Finally, we investigate the tension between information aggregation and spread of misinformation. In Chapter 4, we introduce conflicting interests into a model of non-Bayesian belief dynamics. Agents meet with their neighbors in the social network and exchange information strategically. With conflicting interests, the belief dynamics typically fails to converge: each agent's belief converges to some interval and keeps fluctuating on it forever. Cette dissertation de doctorat développe des théories de l'influence sociale dynamique. Dans un cadre dynamique, les individus interagissent à plusieurs reprises avec leur environnement social et échangent leurs croyances et opinions sur différentes questions économiques, politiques et sociales. Dans le Chapitre 2, nous étudions les processus d'influence modélisés par les moyennes ordonnées pondérées. Ces dernières sont anonymes : elles ne dépendent que du nombre d'agents qui partagent la même croyance. Nous exhibons une condition nécessaire et suffisante pour la convergence au consensus et caractérisons les résultats où la société se retrouve polarisée. Enfin, nous appliquons nos résultats aux quantificateurs linguistiques flous. Dans le Chapitre 3, nous introduisons la possibilité de manipulation dans le modèle de DeGroot (1974). Nous montrons que la manipulation peut modifier la structure de confiance et mène à une société connectée. La manipulation promeut le leadership d'opinion, mais même l'agent manipulé peut gagner de l'influence sur les croyances à long terme. Finalement, nous étudions la tension entre l'agrégation d'informations et le déploiement de désinformations. Dans le Chapitre 4, nous introduisons des conflits d'intérêt dans un modèle de dynamique de croyance non-bayésienne. Les agents se rencontrent avec leurs voisins dans le réseau social et échangent des informations stratégiquement. Avec des conflits d'intérêt, la dynamique de croyance ne converge pas en général : la croyance de chaque agent converge vers un certain intervalle et continue à fluctuer sur celui-ci pour toujours. (ECGE - Sciences économiques et de gestion) -- UCL, 2014