Homophily, selection, and choice in segregation models.

Schelling's 1971 work on the dynamics of segregation showed that even a small degree of homophily, the desire to live among like neighbors, can lead to a starkly segregated population. One of the driving factors for this result is that the notion of homophily used is based on group identities that are exogenous and immutable. In contrast, we consider a homophily that arises from the desire to be with neighbors who are behaviorally similar, not necessarily those who have the same group identity.

Will the Needs-Based Planning of Health Human Resources Currently Undertaken in Several Countries Lead to Excess Supply and Inefficiency?

Recently, the emphasis on health human resources (HHR) planning has shifted away from a utilization-based approach toward a needs-based one in which planning is based on the projected health needs of the population. However, needs-based models that are currently in use rely on a definition of 'needs' that include only the medical circumstances of individuals and not personal preferences or other socio-economic factors. We examine whether planning based on such a narrow definition will maximize social welfare.