| The main purpose of this dissertation is to provide evidence of causal effects of the neighborhood environment on obesity. The first chapter examines the causal effects of urban sprawl on obesity, using exogenous variation in urban sprawl caused by the original plan of the Interstate Highway System. By combining data from the National Health Interview Survey (1976--2001) and the U.S. Census (1970--2000), this chapter assesses the extent to which urban sprawl has contributed to the increase in obesity employing the two-step model. Empirical estimates indicate that about 13% increases in obesity can be attributed to urban sprawl. Further sub-group analyses show that the effects are much stronger for male, more pronounced for the low-educated and whites, while the shift of population to less dense areas has little effects for female and blacks, smaller effect for the high-educated.;The second chapter identifies the role of neighborhood characteristics on obesity using data from a randomized experiment, the Moving to Opportunity for Fair Housing Demonstration (MTO) study, to avoid the endogenous selection problem. In this chapter, I test whether several widely-hypothesized environmental attributes are causes of obesity by linking the MTO Interim Evaluation data with numerous external data sources that provide information on environmental characteristics that the existing literature suggests as potential determinants of obesity, including food prices, restaurant and food store availability, physical activity facility availability, the prevalence of crime and population density. Empirically, measures of these neighborhood contextual factors are added to the basic intention-to-treat model, and the differences in the treatment effects when these variables are and are not included provide indirect evidence of the causal effect of these factors on obesity. I find that the intention-to-treat effects change little after adding the contextual factors, indicating these widely-hypothesized environmental factors are unlikely to be causes of obesity for the low-income women.;Overall, it follows from the results that recent calls to redesign communities to fight against rises in obesity rates need more serious scrutiny, particularly if urban and community redesign are costly and the cost-effective analyses should be exercised when devoting resources to this cause. |
