Lifespan variation for cohorts is declining

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

Lifespan variation is a fundamental dimension of inequality. However, little is known about lifespan variation for real cohorts – the majority of research has focused on the period perspective. We use the Human Mortality Database data to compare adult (ages 30+) lifespan variation for cohorts and periods. Under declining mortality, death rates at adult ages are lower in the cohort perspective. This compresses the lifespan distribution at young ages, decreasing the variation. However, increased old-age survival stretches the right tail of the distribution, increasing variation. We contrast the trends in cohort and period lifespan variation and investigate the age patterns driving the trends. We extend the range of observations by forecasting the mortality of partially observed cohorts. We find that adult cohort lifespan variation is steadily declining, in contrast to the stagnation observed in period perspective.