ECONOMIC-DEMOGRAPHIC DEPENDENCY RATIO IN A LIFE-CYCLE MODEL

The conventional dependency ratio based on cohort-invariant cutoff points could overstate the true burden of population aging. Using optimal cohort-varying years of schooling and retirement age in a life-cycle model, we propose a modified definition of dependency ratio. We compare the proposed economic-demographic dependency ratio (EDDR) with the conventional definition and find that the conventional dependency ratio of the USA is projected to increase by 0.105 from 2010 to 2060, which is an over-projection of 86% when compared with the projected increase of 0.015 in the EDDR over the same period. Sensitivity analysis suggests that our finding is quite robust to reasonable changes in parameter values (except for one parameter), and the magnitude of over-projection ranges mainly from 0.079 to 0.102 (i.e., 75% to 97%). We follow the well-established Lee-Carter model to forecast stochastic mortality and employ the method of expanding duration to decompose the sources of over-projection.