From resource allocation to neighbor selection in peer-to-peer networks

Incluye bibliografía y anexosEn la tesis se estudia primero, desde un punto de vista teórico, las diferentes posibilidades de asignación de recursos de las redes peer-to-peer (P2P) y los incentivos que las mismas proveen a los peers. Luego, se realiza el diseño de un algoritmo que alcanza la asignación deseada manteniendo los incentivos para motivar a los peers a contribuir. Analizando los incentivos aparece un compromiso entre eficiencia y justicia en la red. Se procede a diseñar un algoritmo descentralizado de “selección de vecinos” (donde se elige con quién compartir contenido de manera de alcanzar un óptimo global). El algoritmo se basa en el uso de Cadenas de Markov de tiempo continuo que aparecen en el estudio de la mecánica estadística, en particular las distribuciones de Gibbs. El algoritmo consiste en un Gibbs Sampler, que alcanza la asignación deseada manteniendo sencillez en la implementación. En la última parte de la tesis se extienden las propuestas al contexto de redes inalámbricas ad-hoc, en las cuales el compromiso de eficiencia y justicia cambia radicalmente debido a que la eficiencia de la red está asociada a qué vecinos podemos elegir para comunicar, ya que en las redes inalámbricas las restricciones de capacidad se vuelven par a par, en lugar de una única restricción de subida por peer. Las interferencias entre enlaces debido la comunicación inalámbrica complican aún más el problema. De todos modos, se propone una extensión al algoritmo que logra los objetivos deseados también en este tipo de redes y que permite modular el compromiso entre eficiencia y justicia satisfactoriamente.ANII - POS_NAC_2012_1_9088

Field Experiments in Labor Economics

We overview the use of field experiments in labor economics. We showcase studies that highlight the central advantages of this methodology, which include: (i) using economic theory to design the null and alternative hypotheses; (ii) engineering exogenous variation in real world economic environments to establish causal relations and learning about the underlying mechanisms; and (iii) engaging in primary data collection and often working closely with practitioners. To highlight the potential for field experiments to inform issues in labor economics, we organize our discussion around the individual life cycle. We therefore consider field experiments related to the accumulation of human capital, the demand and supply of labor, behavior within firms, and close with a brief discussion of the nascent literature of field experiments related to household decision-making.

A matter of costs and benefits? The role of morality, legitimacy and self-control as moderators of the link between rationality and youth delinquency in Uruguay

The question about the rationality of crime and violence is not only a controversial issue but also has strong policy implications. Despite the large number of rationality studies in criminology, there is little empirical evidence on how rationality can be moderated by non-rational mechanisms. Additionally, many studies examining the influence of rational choice on crime suffer from several methodological problems associated with small and biased samples, limitations of the dependent variable, varying operationaliations of rationality, and scarce inclusion of validated non-rational causal mechanisms. Finally, there is a lack of cross-cultural validity of rational and non-rational predictors of crime since most studies have been conducted in high-income societies. Little research has examined how well these explanations can fit the socio-economic, cultural and institutional characteristics of the Latin-American context. The goal of this study was to examine a rational choice model of crime and its interactions with three well known non-rational causal mechanisms in criminology: morality, legitimacy and self-control. The study involved the application of a survey on 2,204 9th grade youths from a representative sample of high schools in a middle income society in Latin America: Montevideo, Uruguay. The questionnaire was an adaptation of the Zurich Project on the Social Development of Children Study. The analysis was conducted using count regression models including principal and interaction effects based on a hierarchical or blockwise entry method. Results indicated that rationality plays a robust but modest explanatory role even after including socio-demographic variables and the three non-rational predictors. Rational choice theory was supported as a general theory that accounts not only for general crime but also for property and violent crimes. Additionally, rationality had stronger effects than two of the other three non-rational mechanisms: legitimacy and morality. Different dimensions of rationality were examined. Analyses showed that inner costs and peer reactions have significant associations with all types of youth crime, whereas formidability, parents’ reactions and police reactions did not. Finally, the analysis of interactions suggested that the link between rationality and youth crime is mostly unaffected by self-control as a moderator, and moderately conditioned by legitimacy and morality, particularly the latter. Findings, although provisional in Latin-American context, may provide new insights for future research in rational and non-rational mechanisms of youth crime. Research and policy implications of these findings are discussed.Agencia Nacional de Investigación e Innovació

A Pilot Study of Students’ Ethical Decision Making and Emotional Intelligence

Demand for ethical leaders in agriculture is high to meet 21st century goals, while ethics course offerings in land-grant institutions are limited. The purpose of this case study was to establish a baseline of current University of Arkansas Bumpers College of Agriculture, Food and Life Science (Bumpers College) agriculture and natural resource program students’ ethical decision making (EDM), as measured by the DIT-2, and emotional intelligence (EI), as measured by STEM-B and STEU-B, determine if EI mean scores predict EDM, and identify relationships between EDM or EI and demographic characteristics or lifespan experiences. An online survey design with probability sampling resulted in a 16% overall response rate. Postconventional and N2 scores were slightly below the average reported college student score for EDM. N2 scores indicated respondents were not able to distinguish and rate Postconventional over personal interest items. EI as measured by STEM-B and STEU-B mean scores indicated students could not select correct emotional management or understanding actions with proficiency. STEM-B was not a predictor of DIT-2 N2 scores, but STEU-B which indicated emotional understanding was a predictor of EDM. Only moderate or weak associations were found between demographic and lifespan experience variables and EI and EDM. Study implications and recommendations for EDM, EI and demographic and lifespan experiences are discussed

A Pilot Study of Students’ Ethical Decision Making and Emotional Intelligence

Demand for ethical leaders in agriculture is high to meet 21st century goals, while ethics course offerings in land-grant institutions are limited. The purpose of this case study was to establish a baseline of current University of Arkansas Bumpers College of Agriculture, Food and Life Science (Bumpers College) agriculture and natural resource program students’ ethical decision making (EDM), as measured by the DIT-2, and emotional intelligence (EI), as measured by STEM-B and STEU-B, determine if EI mean scores predict EDM, and identify relationships between EDM or EI and demographic characteristics or lifespan experiences. An online survey design with probability sampling resulted in a 16% overall response rate. Postconventional and N2 scores were slightly below the average reported college student score for EDM. N2 scores indicated respondents were not able to distinguish and rate Postconventional over personal interest items. EI as measured by STEM-B and STEU-B mean scores indicated students could not select correct emotional management or understanding actions with proficiency. STEM-B was not a predictor of DIT-2 N2 scores, but STEU-B which indicated emotional understanding was a predictor of EDM. Only moderate or weak associations were found between demographic and lifespan experience variables and EI and EDM. Study implications and recommendations for EDM, EI and demographic and lifespan experiences are discussed

A Multidisciplinary Study Of Antecedents To Voluntary Knowledge Contribution Within Online Forums

One challenge faced by online forums is the provision of a sustainable supply of contributions of knowledge (Wasco et al., 2009). Previous studies have identified online trust and perceived critical mass as antecedents of online knowledge contributions. However, the dynamic aspects of antecedents are little investigated. Moreover, how the dynamics together impact on members’ willingness to contribute knowledge is an open question to be further investigated. To examine the dynamic antecedents of online knowledge continuance, this thesis seeks to develop a holistic approach through three studies. Drawing on a decomposed theory of planned behaviour (Taylor and Todd, 1995), study one identifies dynamic antecedents of intentional online contribution behaviours. Covariance-based structural equation modelling analysis of 910 responses obtained shows that perceived critical mass and trust in online forums that mediates trust in members are the highlighted antecedents in the context of online forums. The development of trust in online forums is investigated through a time series approach in study two. Findings using webnographic and machine learning analysis show that the cognitive dimension of institutional trust is essential in initial trust building. Study three uses network analysis techniques to explore the role of critical mass members. Results indicate that only 5% of critical mass members can sustain online forums. However, critical mass members compete for their connections, inferring the importance of brand building in the beginning of online forums development. A summary of findings from the three studies suggests that the structure assurance of online forums can mediate the effects of interactions between members to a coalition of membership over time. The study provides further knowledge on the voluntary contribution within online forums by taking a dynamic approach, while previous studies in this field are predominantly cross-sectional and un-prophetic

Essays On Referral Programs And Preference Estimation

In this dissertation, we study referral programs and preference estimation in two essays. In the first essay, we propose that a firm can enhance the effectiveness of its referral program by promoting better matching between referred customers and the firm. We develop three treatments aimed at promoting better matching, including (1) offering current customers a gift before inviting them to refer friends, (2) notifying current customers about the value that they have received from the firm before inviting them to refer friends, and (3) rewarding referring customers based on the value of their referred customers. We test these three treatments by conducting two field experiments in collaboration with a Chinese online financial services firm. We find that all three treatments substantially enhanced the effectiveness of the focal referral program, measured for each current customer as the total value of his referred customers. We also find that the enhancement was primarily driven by the acquisition of higher-value new customers rather than the acquisition of more new customers. In addition, we investigate customer heterogeneity in treatment effects and explore the mechanisms through which these treatments impacted customer referrals. In the second essay, we develop a new model for effective modeling of consumer heterogeneity in choice-based conjoint estimation. Assuming that most variations in consumers\u27 partworth vectors are along a small number of orthogonal directions, we propose that shrinking the individual-level partworth vectors toward a low-dimensional affine subspace that is also inferred from data can be an effective approach to pooling information across consumers and modeling consumer heterogeneity. We develop a low-dimension learning model to implement this information pooling mechanism that builds on recent advances in rank minimization and machine learning. We evaluate the empirical performance of the low-dimension learning model using both simulation experiments and field choice-based conjoint data sets. We find that the low-dimension learning model overall outperforms multiple benchmark models in terms of both parameter recovery and predictive accuracy. While addressing two different marketing topics, both essays share a common theme - careful modeling of consumer heterogeneity plays a key role in understanding consumer behavior and developing effective marketing strategies

Exploring and explaining participation in local opposition : brown coal mining in Horní Jiřetín

This book summarizes a three-year research project on local opposition to coal mining in the Northwestern part of the Czech Republic. The research focused on the relational dimensions of the opposition movement and the political context in which the movement operates. Funding for this project was awarded by the Czech Science Foundation to Masaryk University for the years 2017–2019 (project No. 17-08554Y). The research yielded five peer-reviewed articles that introduced the historical and political context of coal mining in the country (Černoch & Lehotský, 2019), explored the media discourse around coal in the Czech Republic (Lehotský, 2018; Lehotský, Černoch, Osička, & Ocelík, 2019) and around its future in the wider Central European region (Osička et al., 2020), and explored the opposition network attributes (Ocelík, Lehotský, & Černoch, n.d.) as well as the perspectives and discursive positions of the opposition’s representatives (Černoch et al., 2019). The following text recapitulates and expands on these articles

Exploring and explaining participation in local opposition: brown coal mining in Horní Jiřetín

This book summarizes a three-year research project on local opposition to coal mining in the Northwestern part of the Czech Republic. The research focused on the relational dimensions of the opposition movement and the political context in which the movement operates