Ricerc@Sapienza

Estimating the force of mortality (mortality hazard) at the highest ages is a key to understanding the mechanisms that govern human mortality. It has been recently showed that human death rates increase exponentially up to about age 80, thereafter decelerate and reach or closely approach a plateau after age 105. The plateau seems to decline somewhat across cohorts. However, several important research questions are left unsettled. Is selective survival the sole responsible for mortality deceleration and the convergence to the plateau at very old ages? Are there other underlying mechanisms possibly contributing to this process? How is increasing longevity determined? Is mortality at the plateau decreasing over time or is rather the convergence to the plateau that is postponed to older and older ages?
To answer these questions, we will device a statistical model incorporating mortality selection and mathematically implying a mortality plateau at the extreme ages, and simultaneously accounting for yearly health and mortality improvements. Statistical strategies will be also developed to overcome possible estimation problems arising from such complex mortality models. The resulting model will be applied to surfaces of mortality rates over age and time by sex for Italy and possibly for other European countries.