Wage differentials across college majors are huge and have been increasing. The type of college education becomes important for college students in terms of future earnings. Understanding the treatment effect of major choice in a certain occupation is difficult because of the sorting behavior and the effect of occupation choice. In order to accomplish this, I provide a dynamic model that combines major choice with occupation choice. The simulation results illustrate that science majors earn 30% more if they choose jobs related to science. However, this high premium does not exist in all jobs. The major choice itself does not guarantee a high return. Occupation choice matters a lot in obtaining a higher premium. The second chapter proposes a dynamic model of college course and occupation choices, where individuals make human capital investment under imperfect information about the future return. Using simulation results based on this model, I investigate the role played by uncertainty in student choices. I contribute to the recent task-based heterogeneous human capital literature by adding choices made before individuals enter the labor market. By combining college transcript data and occupational knowledge requirement information, I match human capital with occupational tasks to better evaluate the labor market performance of college graduates. For tractability purposes, both human capital and occupational tasks are aggregated into two dimensions: STEM and non-STEM. Estimation results indicate that college courses have different returns at work, with STEM courses inducing relatively higher wages. When uncertainty is eliminated, individuals specialize more in STEM or non-STEM based on their comparative advantages. The change of specialization in STEM courses is bigger compared to non-STEM courses. Overall benefits of human capital specialization are more pronounced in top ranking colleges. Old-age medical expenditure risks have been documented to impose significant impacts on elderly savings. However, little is known about the consumption effects of elderly medical expenditure risks. In this study, we examine the effect of medical expenditure risk on elderly household consumption decisions. We identify the causal effect by exploiting the exogenous reduction in prescription drug spending risk as a result of the introduction of Medicare Part D in the U.S. in 2006. Using the Health and Retirement Study (HRS) data during 2004 - 2010, we find that declining medical expenditure risks had little impact on total consumption, regardless of nondurable or durable consumption.