The changing impact of regional inequalities in mortality on individual variation in lifespan

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

Subpopulation age-at-death distributions can differ from one another because of differences in average lifespan (between-group inequalities) as well as differences in how individual lifespans are distributed within the group (within-group variation). Using additive subgroup decomposition techniques, the individual lifespan variation of the total population can be decomposed into these two components. The contribution of the stratifying variable being examined, for example socioeconomic status, smoking, or region, is simply the between-group inequality component divided by the total individual variation. In this paper I apply these methods to measure the contribution of regional inequalities in mortality to individual lifespan variation. I use broad regional demarcations in three countries: the United Kingdom (Scotland, Northern Ireland, England & Wales), Germany (East and West Germany) and Canada (the provinces). Using data from the Human Mortality Database and the Canadian Human Mortality Database, I respectively decompose the male and female lifepan variation into its between- and within-region components, for each year from 1956-2005. Although the region of residence is explaining only a small proportion of all individual variation in age-at-death, the results from this study show large changes in this contribution over time. In further analysis I apply the decomposition technique developed by Mookherjee and Shorrocks (1982) which allows me to disentagle whether changes in this component over time were due to changes in within-region variation, changes in relative mean lifespans or compositional changes to the between or within group components. By separately examining changes to the between- and within-group components of lifespan variation, we get a different, but complementary picture to traditional methods that focus on regional inequalities as being average differences between regions. Reducing regional inequality requires both raising the average lifespan of disadvantaged areas as well as reducing the dispersion around this average.