Extrapolative projections of mortality: towards a more consistent method. The central scenario and study of estimation errors
Dalkhat M. Ediev, Vienna Institute of Demography
The paper advocates using the direct extrapolation of mortality by age and sex for mortality projections. The method is supplemented by additional procedures in order to improve its efficiency in the short-run and preclude implausible mortality patterns in the long-run. The short-run efficiency is improved by building the forecast on data from the most recent periods, when mortality dynamics exhibits steady trend. In the long-run, the rates of mortality decline are assumed to converge to a plausible function of age and sex, which is derived from the data based on the assumption that it is a monotonic function of age. The framework provides basis for introducing uncertainty into the projection. Simulations were run to study estimation errors of model parameters and autocorrelations involved. They also indicate that estimates of some of the parameters are ineffective and may lead to wrong conclusions with respect to the mortality dynamics.