The cross-sectional average inequality in lifespan (CAL†): A lifespan variation measure that reflects the mortality histories of cohorts

Abstract

Lifespan variation is a key metric of mortality that describes both individual uncertaintyabout the length of life and heterogeneity in population health. We propose a novel andtimely lifespan variation measure, which we call the Cross-sectional Average Inequality in Lifespan. This new index provides an alternative perspective on the analysis of lifespan inequality by combining the mortality histories of all cohorts present in a cross-sectional approach. We demonstrate how differences in the Cross-sectional Average Inequality in Lifespan measure can be decomposed between populations by age and cohort to explore the compression or expansion of mortality in a cohort perspective. We apply these new methods using data from ten low-mortality countries from 1879 to 2013. The Cross-sectional Average Inequality in Lifespan measure reveals greater uncertainty in the timing of death than the period life table-based indices of variation indicate. Also, country rankings of lifespan inequality vary considerably between period and cross-sectional measures. These differences open intriguing questions as to which temporal dimension is the most relevant to individuals when considering the uncertainty in the timing of death in planning their life courses.