BACKGROUND

The Indigenous Mortality Project linked around 21 million records from the 2011 Census with 153,455 death registrations where the death occurred on or after 10 August 2011 and was registered by 27 September 2012. The time period of death registrations was selected in order to capture as many deaths as possible of people who were counted in the 2011 Census (which took place on 9 August 2011). Due to time lags between occurrence and registration, the number of deaths registered during this period would be lower than the number of deaths that occurred, particularly for those deaths occurring towards the end of the reference period.

The 2011 Census processing period, like the 2006 Census, provided the opportunity to link death registrations with Census records using name, address and other variables common to both datasets. It should be noted that all names and addresses collected in the Census were destroyed at the conclusion of Census processing on 7 December 2012, setting an end point to the Gold Level Standard linkage period.

Death registrations data are a key input for estimating life expectancy and are provided to the ABS as an administrative dataset by the state and territory Registries of Births, Deaths and Marriages. Whilst most deaths for Aboriginal and Torres Strait Islander people are registered, in some instances the Indigenous status is not correctly identified, or identified inconsistently with respect to the Indigenous status in the Census.

The aims of the Indigenous Mortality Project were to:

• assess the consistency of Indigenous status as reported in death registration and Census data
• estimate measures of under-identification of deaths for Aboriginal and Torres Strait Islander people by state/territory and remoteness areas of Australia
• investigate the feasibility of applying adjustment factors for Aboriginal and Torres Strait Islander deaths output data
• provide input into the compilation of life tables and life expectancy estimates for Aboriginal and Torres Strait Islander people and non-Indigenous people, as well as Aboriginal and Torres Strait Islander/non-Indigenous differences in other mortality measures, that are consistent with population estimates based on the adjusted 2011 Census of Population and Housing.

DATA LINKING PROCESS

The Indigenous Mortality Project expanded on the methods used in the 2006 quality study, as described in the research paper Linking Census Records to Death Registrations (cat. no. 1351.0.55.030).

Detailed information on Indigenous Mortality Project methodology and linkage quality is available in Information Paper: Death Registrations to Census Linkage Project — Methodology and Quality Assessment Australia 2011–12 (cat. no. 3302.0.55.004).

Data Security

Confidentiality of data used for linking was maintained in accordance with the High Level Principles for Data Integration involving Commonwealth data for Statistical and Research Purposes endorsed by the Secretaries Board in 2010. Operational arrangements for managing data flows within the ABS included restricting access to information through the functional separation of roles. These roles ensured that no-one could see identifying information in conjunction with the content data; that is, staff could see only the information they needed to undertake the linking or analysis. For more information refer to the 'separation principle' on the National Statistical Service website.

All data preparation, linking and clerical review was performed using password-protected remote virtual servers located within the Census Data Processing Centre (DPC) environment.


ABORIGINAL AND TORRES STRAIT ISLANDER PEOPLE'S IDENTIFICATION IN DIFFERENT DATA COLLECTION CONTEXTS

The Indigenous Mortality Project brings together data from two different data collection contexts, and two different respondents. The context in which Indigenous status information is being provided, and who is providing the information, can influence whether a person is identified as being of Aboriginal and/or Torres Strait Islander origin (see the National Best Practice Guidelines for data linkage activities relating to Aboriginal and Torres Strait Islander people for general information on this).

The ABS conducted research in 2010 and 2012 to understand issues surrounding and contributing to Aboriginal and Torres Strait Islander people's propensity to identify in different data collection contexts. This work took the form of focus groups, facilitated by external consultants in locations around Australia. The focus group research conducted in 2010 focused on identification in administrative data collections, and the 2012 research sought to understand identification behaviours in survey contexts.

Participants noted a wide range of factors influencing their decision to identify as being of Aboriginal and/or Torres Strait Islander origin, including:

• Pride and confidence in identity
• The perception that identifying may lead to positive impacts for the individual and/or the wider Aboriginal and Torres Strait Islander community
• The amount of information available about the reasons why Indigenous status is being collected
• The content, purpose and relevance of the survey
• The belief and experience that identifying may lead to racism, discrimination or differential treatment
• The impact of social environment on identification, and change in the environment surrounding identification in recent decades.

Detailed findings from the research is available in Perspectives on Aboriginal and Torres Strait Islander Identification in Selected Data Collection Contexts, 2012 (cat. no. 4726.0).

Collection of death registrations data for Aboriginal and Torres Strait Islander people

Death registrations data from the state and territory Registries of Births, Deaths and Marriages are used by the ABS to produce estimates of Aboriginal and Torres Strait Islander deaths. The information relates to all registered deaths including those referred to a coroner. Prior to 2007, Indigenous status was supplied to the ABS based on information recorded on death registration forms; that is, as reported by a relative or person acquainted with the deceased, or by an official of the institution where the death occurred. While there is some variation in practice among the jurisdictions, information supplied on both the death registration form and the Medical Certificate of Cause of Death (completed by medical practitioners) has been used where available to derive Indigenous status since 2007. Estimates of Aboriginal and Torres Strait Islander deaths are used as an input for calculating Aboriginal and Torres Strait Islander population and life expectancy estimates.

Collection of Census data for Aboriginal and Torres Strait Islander people

The Census is usually completed by a responsible adult answering for themselves or on behalf of another person (for example, their child) present in the dwelling on Census night. In the standard Census form (both e-forms and paper forms), Indigenous status is provided by the person completing the form, and in some instances may not be reported. In discrete Aboriginal and Torres Strait Islander communities, an interview approach is used, with local people employed and trained to conduct interviews. The Interviewer uses the Interviewer Household Form to collect Census information verbally from a household member, resulting in a lower non-response rate for all items, including Indigenous status. In some urban areas, increased support and assistance is provided to Aboriginal and Torres Strait Islander people, including the option of providing Census information through an interview.

Differential reporting of Indigenous status on the death registration record and in the Census

In addition to differential reporting which may be due to people's propensity to identify themselves or others differently in different data collection contexts, there may be an increased risk of differential reporting of Indigenous status when different people report information that relates to the same person. Whilst there will be instances where death registration and Census information has been provided by the same person (e.g. a family member), it is also possible that Indigenous status may have been recorded by a person not close to the deceased person, which increases the likelihood of inconsistent Indigenous status information between data sources.


OTHER NATIONAL MORTALITY DATA LINKAGE PROJECTS ABOUT INDIGENOUS PEOPLES

The Australian Institute of Health and Welfare conducted a feasibility study that linked 2001–2006 death registrations with three other administrative data sources, using an 'ever-Aboriginal and Torres Strait Islander' approach to determine Indigenous status. The feasibility study produced similar national level life expectancy estimates as the ABS' 2006 CDE Indigenous Mortality Project (Endnote 1).

A New Zealand project linked mortality records for Maori (or Pacific) peoples to Census records, with the aim of investigating numerator-denominator bias in the calculation of mortality rates (Endnote 2). The project found that mortality rates are subject to a numerator-denominator bias and recommended the use of age-specific adjustment ratios for correcting ethnicity-specific mortality rates (Endnote 2).


ENDNOTES

1. Australian Institute of Health and Welfare 2012, An enhanced mortality database for estimating Indigenous life expectancy: a feasibility study, Cat. no. IHW 75. Canberra: AIHW. <www.aihw.gov.au>.

2. Ajwani, S., Blakely, T., Robson, B., Atkinson, J. and Kiro, C. 2003 'Unlocking the numerator-denominator bias III: adjustment ratios by ethnicity for 1981–1999 mortality data. The New Zealand Census-Mortality Study,' The New Zealand Medical Journal Vol 116 No 1175. <www.nzma.org.nz>.

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