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...

As previously argued, the correlation between included and omitted regressors generally causes inconsistency of standard estimators for count data models. Using a specific residual function and suitable instruments, a consistent generalized method of moments estimator can be obtained under...

Vulnerability to scarcity or to reduction of natural capital depends on defensive substitution possibilities that, in turn, are affected by the availability of other productive factors. However, in several developing countries asset distribution tends to be highly skewed. Taking into ac- count...

This paper presents a simple model of search and matching between consumers and firms. The firm size distribution has a Pareto-like right tail if the population of consumers grows at a positive rate and the mean rate at which incumbent firms gain customers is also positive. This happens in...

This paper extends Carroll's (2006) endogenous grid method and its combination with value function iteration by Barillas and Fernández-Villaverde (2007) to non-concave problems. The method is illustrated using a consumer problem in which consumers choose both durable and non-durable...

We propose a novel method to model an agent who is imperfectly attentive in the sense that she may consider only some of the alternatives available. Our methodology departs from the standard 'revealed preference' one: we make plausible assumptions on the values to the imperfectly attentive agent...