Life expectancy is a broad measure of a population’s long-term health and wellbeing. The Council of Australian Governments (COAG) has set a target of closing the life expectancy gap between Aboriginal and Torres Strait Islander and other Australians within a generation (see Overcoming Indigenous Disadvantage: Key Indicators 2011, available at www.pc.gov.au). So that progress toward this target can be more accurately measured, COAG has funded the Australian Bureau of Statistics (ABS) to undertake an ongoing program of work to improve the quality of life expectancy and other mortality estimates for the Aboriginal and Torres Strait Islander population.
This paper presents information on the methodology and quality of the statistical data integration project that linked death registrations to the 2011 Census of Population and Housing. This project, which has been referred to as the Indigenous Mortality Project, was conducted as part of the 2011 Census Data Enhancement program and built on the foundation of the first such study conducted in conjunction with the 2006 Census. The primary aim of the linkage was to assess the consistency of the identification of Indigenous status as reported in death registration and Census data, and thereby provide input into the compilation of life tables and life expectancy estimates for Aboriginal and Torres Strait Islander people.
Death registrations are provided to the ABS by State and Territory Registrars of Births, Deaths and Marriages. This project used information from deaths that were registered during the Census processing period in 2011-12 when Census name and address were available as linking variables. Probabilistic linking methods were used to bring the datasets together and identify the best match. This process involves comparing several variables common to both files and generates a single numerical measure of how well two particular records match.
In addition to advances in technology and data linking software, one of the main improvements was the allocation of greater resources to clerical review. This enabled a high level of quality control through manual checking to the point where virtually all links assigned in this project are assessed as true links; that is, the death registration and Census record belong to the same individual.
At the completion of the linkage, 93% of death registrations had been linked to a Census record. The raw linkage rate for Aboriginal and Torres Strait Islander deaths was 80%, a considerable improvement over the corresponding figure of 74% in the 2006 Census study.
While the Census aims to count every person in Australia on Census Night, inevitably some people are missed. It could be expected, therefore, that not all death registrations will in fact have a corresponding record in the Census file. After applying an adjustment factor to account for people who were missing from the Census, the linkage rate for Aboriginal and Torres Strait Islander deaths rises to about 90% compared with an adjusted linkage rate of 96% for non-Indigenous deaths.
This information paper is the first report to be released from the 2011 cycle of the Indigenous Mortality Project. Two other reports will present statistics from the project including differences in the identification of Indigenous status between death registrations and the Census. One examines the characteristics of linked and unlinked records for Aboriginal and Torres Strait Islander deaths in more depth (Death registrations to Census linkage project - Key Findings for Aboriginal and Torres Strait Islander peoples, 2011-12, cat. no. 3302.0.55.005) and the other presents mortality statistics including life expectancy estimates by Indigenous status (Life Tables for Aboriginal and Torres Strait Islander Australians, cat. no. 3302.0.55.003). These reports are due for release in November 2013.