This paper investigates the degree to which the local prevalence of AIDS increases the demand for disease-preventing methods of contraception among young adults. Using data from the National Longitudinal Survey of Youth (NLSY), we find substantial evidence that the use of condoms was quite...

This paper analyzes how markets for old-age care respond to the aging of populations. We consider how the biological forces, which govern the stocks of frail and healthy persons in a population, interact with economic forces, which govern the demand for and supply of care. We argue that aging,...

This paper discusses the definition and identification of external treatment effects and experimental designs capable of detecting these effects. External effects occur when the outcome of a given individual is affected by the treatment assignments of other individuals. The paper argues that...

This paper provides a theoretical and empirical examination of the long-run growth in weight over time. We argue that technological change has induced weight growth by making home- and market-production more sedentary and by lowering food prices through agricultural innovation. We consider how...