My dissertation comprises three essays in applied microeconomics. They mostly focused on the evaluation and recommendation of policy issues in the fields of health economics and labor economics, with a direct objective toward to alleviate inequality, and to promote efficient and effective economic policies. The first essay studies how the coverage of health insurance can contribute to obesity (BMI index). First, I extend the the theoretical model of Ehrlich and Becker (1972) to find the relationship between health insurance and obesity; and then supplement the theoretical findings with empirical evidence, using BRFSS data from 2001to 2011 among American young adults. IV regression approach and Lewbel IV (2007) techniques were used to estima...