What Can Be Learnt by Studying the Adult Modal Age at Death?

Jean-Marie Robine, Institut National de la Santé et de la Recherche Médicale (INSERM)
Siu Lan Karen Cheung, Institut National de la Santé et de la Recherche Médicale (INSERM) and Demographie et Sante

Averaging all individual life durations in a unique value, life expectancy at birth remains one of the most popular longevity indicators. Its main feature is a high sensitivity to changes in infant mortality. However, this historical advantage becomes less obvious when mortality chiefly concerns elderly populations. In this context, the specificity of the modal age at death (M), determined only by adult mortality, provides a good account of the most common longevity. For instance, M reached 91 years for women in Japan in 2002, about six years more than the life expectancy at birth. We claim that decomposing the question of human longevity into two components - how many babies become adult and how long adult life spans are – will provide meaningful insights. Using all the data available in the Human Mortality Database (HMD), we illustrate our proposal with various life table functions at M.