We developed a structural model of network formation and behaviour with the aim of decomposing the observed positive correlation of academic performance of individuals and that of their peers. The model is a general purpose one in the sense that with appropriate modifications it can be applied to many of the several contexts in which such correlations have been observed. Having said this, several modelling choices were strongly influenced by special features of the two main settings in which we conducted our empirical work : A European elite university (with Giacomo De Giorgi, Isabel Melguizo and Michele Pellizzari) (Dataset 2) and an elite University in Bogotá, Colombia, (with Juan Camilo Cárdenas) (Dataset 1).
The main findings based on Dataset 1 was a positive correlation between how trusting the subjects were, as revealed by the trust experiment, and their closeness centralities in various of the networks of relations that we uncovered via surveys. This finding prompted us (with Davide Pietrobon and Danisz Okulicz) to propose a simple modification of a model of network formation introduced by Jackson and Rogers in 2007, to allow for heterogeneity in agents’ mean willingness to form a link conditional on any given meeting opportunity. Provided that this propensity to form a link is related to agents’ willingness to trust, the model offers a variety of simple novel implications on the relationships between agents’ levels of trust, their degrees in their networks of relationships, the degree distributions of their friends and the distribution of trust among them, their positions in their networks, and in particular their centralities.
Most of the work throughout the action focused on (Datset 2). Using this Dataset we obtained estimates of the structural parameters of our theoretical model,
and in particular were able to decompose the observed correlation in the academic achievement of individuals and that of their peers between assortativity and influence under reasonable assumptions. In addition to estimating the parameters of the model related to this decomposition, which was the main objective of this part of the project, we were able to estimate parameters reflecting the role played in network formation of individual characteristics other than academic skills and performance, such as gender and region of origin.
