We consider an economy in which a heterogeneous population of agents have to choose among a common set of alternatives. The utilities associated to the different alternatives posses a common component and an individual component, which reflect differences in the underlying structure of agents...

Ellison and Glaeser's (1997) index of geographical concentration distinguishes between natural advantages and spillovers as a source of industrial agglomeration, but the well-known 'observational equivalence' means little is known about the relative importance of these. This paper uses the...