His research focuses on the health of populations. His work encompasses three interconnected areas: social and policy determinants of health and dynamics of health disparities; population heterogeneity and dynamics of obesity, aging and mortality; medical expansion and population health. His ongoing work addresses (1) the effect of selection bias and unobserved heterogeneity in the process of health production, the trends of aging, obesity, health disparities and life expectancy; (2) the role of cohort forces in life course of health and mortality pattern; (3) the recent trend in mortality and health disparities in the U.S; (4) the effect of sex ratio and marriage market on health; (5) the effect of medical expansion on population health; and (6) working place and health.