Title: Heterogeneity’s Ruses: The Impact of Mortality Selection on Dynamics of Health Disparity and Life Expectancy
Abstract: Unobserved individual frailty is prevalent and consequential in the population pattern of health and mortality. This study investigates how unobserved frailty may complicate the cohort trend in health disparity and life expectancy. Simulation exercises reveal that in the absence of a change in the individual mortality curve, life expectancy can increase or decrease across birth cohorts due to the increase or decrease in variance of frailty distribution. In the absence of a change in the causal effect of education on mortality at the individual level, an educational life expectancy gap can either widen or narrow across cohorts as a result of the change in frailty variance. I further propose a counterfactual simulation procedure to evaluate the contribution of mortality selection to the cohort trend in educational life expectancy gap in the U.S. Using the number of diseases before age 17 from Panel Studies of Income Dynamics and National Health and Nutrition Examination Survey data as a proxy for frailty and cohort age-dependent mortality pattern from National Health Interview Survey data, I find mortality selection inflates educational life expectancy gap among women while offsets widening educational life expectancy gap among men from the 1950s to 1960s cohorts.
