Lifespan Inequality

Mean longevity and equality of lifespans can move in different directions. Life expectancy at birth summarizes mean longevity but hides the spread of ages at death. Life expectancy alone is inadequate for assessing demographic progress because it can hide divergence in young adult mortality and lifespan inequality. Lifespan inequality is measured as the variance in age at death and represents dispersion around the mean age at death. Adult lifespan inequality V(15) excludes infant and childhood mortality and is the study's main adult inequality measure. Lifespan variation describes individual uncertainty about age at death and how evenly mortality conditions are shared. Lifespan inequality can either decrease or increase after mortality decline depending on the age at which mortality falls. Postwar fluctuations in adult lifespan inequality were mainly driven by mortality changes at young working ages. The note argues that relative lifespan equality should not be interpreted as mathematically linked to life expectancy through a shared perturbation weight alone. Relative lifespan equality measures in the article are constructed by normalizing an absolute inequality measure by life ex…