The behaviour of urban populations is compared with the systems directing behaviour in individuals. This is both a metaphor and a mechanistic parallel. The biological model draws upon recent developments in brain research and psychological and cultural anthropology. The development and operation...

The emergence of competition is a defining aspect of human nature and characterizes many important social environments. However, its relationship with how social groups are formed has received little attention. We design an experiment to analyze how individuals' willingness to compete is...

Many Social Interactions display either or both of the following well documented phenomena. People tend to interact with similar others (homophily). And they tend to treat others more favorably if they are perceived to share the same identity (in-group bias). While both phenomena involve some...

We exploit the randomized evaluation of a remedying education intervention that improved the reading skills of low-performing third grade students in Colombia, to study whether providing educational support to low-achieving students affects the academic performance of their higher-achieving...

This paper studies whether conformism behavior affects individual outcomes in crime. We present a social network model of peer effects with ex-ante heterogeneous agents and show how conformism and deterrence affect criminal activities. We then bring the model to the data by using a very detailed...

This article relies on a large-scale field experiment in Mexico to measure the effects of two ability-grouping models (tracking and heterogeneous/bimodal groups) on student learning outcomes during middle school. Both strategies yielded an average learning gain of 0.08 of a standard deviation....