Quantifying the Demographic Drivers of Subnational Population Ageing: The Case of Australia

Tom Wilson , The University of Melbourne
Jeromey Temple, The University of Melbourne

The conventional wisdom in demography is that population ageing is primarily the result of fertility decline. However, this view has been challenged by a number of studies in recent years which indicate a dominant role for mortality improvement in more developed countries. Many of these studies use decomposition to quantify the drivers of population ageing and have made valuable additions to our understanding of population ageing at the national scale. But relatively little attention has been paid to the subnational scale where demographic trends often differ substantially. The aim of this paper is to understand the demographic drivers of contemporary population ageing in large subnational regions. A case study of ageing amongst Australia’s states and territories over the period 2001-16 is presented. Population ageing was measured by an increase in the mean age of the population, and the Preston, Himes & Eggers method was used to decompose mean age changes into contributions from births, improvements in survival, and net migration. The necessary input data for the period 1901 to 2016 were obtained primarily from the Australian Bureau of Statistics and the Australian Demographic Databank. We find that although the amount of population ageing varied moderately between states and territories, the demographic drivers varied enormously in extent and relative importance. In some cases, fertility contributed the most to ageing while in others mortality improvement was dominant. Net migration worked to reduce the effects of ageing in most states and territories – with one key exception.

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 Presented in Session P2. Poster Session Ageing, Health and Mortality