Decomposing Lifespan Inequality by Subgroup, with an Illustration on Sex Differences in Mortality

Alyson A. van Raalte, Max Planck Institute for Demographic Research

The average difference in lifespan between individuals is currently between 7.4 and 10.5 years in the most economically advanced economies. Meanwhile, groups disadvantaged in life expectancy tend to also have greater dispersion in the age at death. Yet how much the differences in lifespan inequality between subgroups can account for the total lifespan inequality to date remains unknown. Using Theil’s entropy index, the contribution of subgroup dispersion to total dispersion in the age at death can be determined, by additively decomposing the total inequality into within- and between-group inequality. This study gives an example related to sex inequalities in lifespan, but the method could equally be applied to quantifying the contribution of socioeconomic, racial, or regional lifespan inequalities to the total dispersion in age at death. Such studies will contribute to a better understanding and interpretation of the causes of total lifespan inequality, including the between-country variations in these inequalities.