Dynamic Modelling of Mortality Via Mixtures of Skewed Distribution Functions

Abstract

Abstract There has been growing interest on forecasting mortality. In this article, we propose a novel dynamic Bayesian approach for modelling and forecasting the age-at-death distribution, focusing on a three-component mixture of a Dirac mass, a Gaussian distribution and a skew-normal distribution. According to the specified model, the age-at-death distribution is characterized via seven parameters corresponding to the main aspects of infant, adult and old-age mortality. The proposed approach focuses on coherent modelling of multiple countries, and following a Bayesian approach to inference we allow to borrow information across populations and to shrink parameters towards a common mean level, implicitly penalizing diverging scenarios. Dynamic modelling across years is induced through an hierarchical dynamic prior distribution that allows to characterize the temporal evolution of each mortality component and to forecast the age-at-death distribution. Empirical results on multiple countries indicate that the proposed approach outperforms popular methods for forecasting mortality, providing interpretable insights on its evolution.