Probabilistic Projection of Subnational Life Expectancy

Hana Sevcikova, University of Washington
Adrian Raftery, University of Washington, Seattle

Projecting mortality for subnational units is of great interest to practicing demographers. We seek a probabilistic method for projecting subnational life expectancy that is based on the national Bayesian hierarchical model used by the United Nations, and is easy to use. We propose three methods of this kind. Two of them are variants of simple scaling methods. The third method models life expectancy for a region as equal to national life expectancy plus a region-specific heteroskedastic first-order autoregressive process (AR(1)), with a variance that declines to a constant as life expectancy increases. We apply our models to data from 29 countries. In an out-of-sample comparison, the proposed methods outperformed other comparative methods and were well calibrated for individual regions. The AR(1) method performed best in terms of crossover patterns between regions. Although the methods work well for individual regions, there are some limitations when evaluating within-country variation. In addition to providing the full distribution of subnational life expectancy, the methods can be used to obtain probabilistic forecasts of age-specific mortality rates.

Keywords: Mortality, Bayesian methods / estimation, Population projections, forecasts, and estimations

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  Presented in Session 135. Formal Models and Methods for the Analysis of Mortality and Causes of Death