The Growth of Australia's Very Elderly Population: Past Estimates and Probabilistic Forecasts

Official population estimates in Australia are overstated at the very highest ages, resulting in inaccurate mortality rates, and unreliable forecasts. Official population forecasts are not accompanied by information about their uncertainty, and do not extend into the centenarian ages. The aim of this chapter is to present more accurate estimates of the very elderly population of Australia (those aged 85+) from 1971 to 2014, and probabilistic forecasts out to 2051 by sex and single years of age up to age 110+. Population estimates were calculated from death counts using Extinct Cohort and Survivor Ratio methods, the latter being a newly-refined version. Population forecasts were produced using a probabilistic cohort-component model. The 85+ population of Australia grew from 69,000 in 1971 to 456,000 in 2014, in large part due to mortality reductions. It is forecast to increase to 1.90 million by 2051, with the 95 % prediction interval spanning 1.51 to 2.37 million. The future growth in centenarians is proportionally far greater, but relatively more uncertain. Although the extent of future growth cannot be forecast precisely, huge increases in Australia’s very elderly population will eventuate.