Forecasting Life Expectancy in an International Context

Tiziana Torri, Università di Roma "La Sapienza" and Max Planck Institute for Demographic Research

Many factors influencing mortality are not limited to their country of discovery—both germs and medical advances can transcend borders. How can we consider the impact of common factors on the future mortality of different countries? We suggest using a country-aggregated measure of mortality, the best-practice line, to obtain better forecasts of life expectancy at the national level. Over the past 160 years, female best-practice life expectancy has been extraordinarily linear. This phenomenon was first observed by Oeppen and Vaupel (2002), who suggested that life expectancy could be forecasted in individual countries by considering the gap in national performance in comparison to the best-practice level. We apply this logic by modeling and forecasting the best-practice level with the classic univariate ARIMA model. Diverse models are instead used for the gap. Correlation among different countries is considered and the uncertainty in the forecast is combined together via Monte Carlo simulation.