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6 The Remoteness Structure divides each state and territory into several regions on the basis of their relative access to services. Remoteness Areas (RA) are the spatial units that make up the Australian Statistical Geography Standard (ASGS) Remoteness Structure. There are six classes of Remoteness Area in the Remoteness Structure: Major Cities of Australia, Inner Regional Australia, Outer Regional Australia, Remote Australia, Very Remote Australia and Migratory.
7 Within a state/territory, each RA represents an aggregation of non-contiguous geographical areas which share common characteristics of remoteness.
8 While statistical data classed to this structure may be available by state/territory, characteristics of remoteness are determined in the context of Australia as a whole. Therefore, not all RAs are represented in all states and territories.
9 For further information see Australian Statistical Geography Standard (ASGS): Volume 5 - Remoteness Structure, July 2016 (cat. no. 1270.0.55.005).
METHOD FOR PRODUCING LIFE TABLES
10 A life table is a statistical model used to represent mortality of a population. In its simplest form, a life table is generated from age-specific death rates and the resulting values are used to measure mortality, survivorship and life expectancy.
11 A life table may be complete or abridged, depending on the age intervals used in their compilation. Life tables in this release are abridged life tables - they contain data for five-year age groups - and are presented separately for males and females. Abridged life tables were chosen as age-specific death rates for five-year age groups were considered more reliable than those for single years of age due to the small annual numbers of Aboriginal and Torres Strait Islander deaths in the states and territories.
12 To construct a life table, data on deaths that occur in a period and estimates of the population (at the mid-point of the period) exposed to the risk of dying are required, disaggregated by age and sex.
13 The first step in the compilation of a life table involves the calculation of age-specific death rates (ASDRs) for the population of interest. ASDRs are calculated as:
14 The next step is to derive mortality rates (the proportion of people of a given age who die within one year, denoted by qx) from ASDRs. The mortality rates are then applied to a hypothetical group of newborn babies (typically 100,000 in size) until the population has died out. This results in a range of related functions, of which the life tables in this release include:
15 The life tables in this release are abridged life tables, based on the average number of Aboriginal and Torres Strait Islander deaths registered in 2015-2017 and final Aboriginal and Torres Strait Islander population estimates for 30 June 2016 based on the 2016 Census results (mid-point between the 2015-2017 reference year). Abridged life tables assume that as a group of new-born babies pass through life it will experience the mortality rates of the specific period which do not change from year to year. Period life tables thus constitute a hypothetical model of mortality, and, although based upon mortality rates from a real population during a particular period of time, do not describe the future mortality of this group.
Life tables for the non-Indigenous population
16 Life tables for the non-Indigenous population were produced to enable a comparison of life expectancy at birth and other ages between the Aboriginal and Torres Strait Islander and non-Indigenous populations of Australia.
17 Numbers of non-Indigenous deaths were obtained by subtracting the adjusted average number of Aboriginal and Torres Strait Islander deaths in 2015-2017 from the total number of deaths registered in 2015-2017 and dividing by three to obtain the average annual number of non-Indigenous deaths.
18 Final estimates of the non-Indigenous population for 30 June 2016 from Estimates of Aboriginal and Torres Strait Islander Australians, Jun 2016 (cat. no. 3238.0.55.001) were used as denominators in the calculation of age-specific death rates for the non-Indigenous population, and life tables derived from these.
Graduation of life tables
19 Graduation refers to a standard demographic technique of smoothing to remove the effect of year to year volatility in numbers of deaths (by age and sex) on mortality rates (qx). This ensures that implausible results do not occur in the life tables, such as female mortality rates exceeding male mortality rates.
20 Life tables were first produced for the Aboriginal and Torres Strait Islander and non-Indigenous populations as described above. While numbers of deaths were averaged for 2015-2017, the resulting mortality rates still contained some volatility across age groups. Mortality rates were therefore adjusted so that the rates were smooth across age groups. This was done for both Aboriginal and Torres Strait Islander and non-Indigenous life tables, for all states and territories and both sexes.
21 The graduation of life tables was performed so that life expectancy at birth estimates were unaffected, but minor changes to life expectancy at other ages occurred.
Victoria, South Australia, Tasmania and Australian Capital Territory
22 The compilation of life tables requires sufficient numbers of deaths to allow the calculation of reliable ASDRs for each age group. With small numbers of deaths the resulting ASDRs are likely to be volatile, and, particularly at younger ages, may be zero.
23 Due to the small Aboriginal and Torres Strait Islander populations of Victoria, South Australia, Tasmania and the Australian Capital Territory, these jurisdictions record very small numbers of Aboriginal and Torres Strait Islander deaths annually (around 167, 186, 52 and 19 Aboriginal and Torres Strait Islander deaths per year on average for 2015-2017 respectively). Disaggregating the numbers of Aboriginal and Torres Strait Islander deaths in these jurisdictions by 5 year age groups to 85 years and over and by sex results in extremely small numbers of deaths for any age group and sex, from which it is not possible to calculate reliable age-specific death rates. For this reason it is not possible to produce reliable life tables for the Aboriginal and Torres Strait Islander populations of these jurisdictions.
Life expectancy in Deaths, Australia (cat. no. 3302.0)
24 Estimates of life expectancy at birth for the total population presented in this release differ from estimates published in Life Tables, States, Territories and Australia, 2015-2017 (cat. no. 3302.0.55.001). Estimates presented in this release are derived from abridged life tables with an upper age limit of 85 years and over, using adjusted numbers of deaths registered in 2015-2017 and the population as at 30 June 2016, while life expectancy estimates in Life Tables, States, Territories and Australia, 2015-2017 (cat. no. 3302.0.55.001) are based on complete life tables with an upper age group of 120 years and over, using deaths according to month of occurrence in 2015-2017 and quarterly population estimates. In addition, graduation processes applied to both sets of life tables differ.
Life expectancy by Index of Relative Socio-Economic Disadvantage (IRSD)
25 Life expectancy at birth estimates by the Index of Relative Socio-Economic Disadvantage (IRSD) are presented in Chapter 1: Life expectancy at Birth. These estimates have been produced using the same methodology as for states/territory, Australia and remoteness areas.
26 The Census and Statistics Act 1905 provides the authority for the ABS to collect statistical information, and requires that statistical output shall not be published or disseminated in a manner that is likely to enable the identification of a particular person or organisation. This requirement means that the ABS must take care and make assurances that any statistical information about individual respondents cannot be derived from published data.
27 Where necessary, tables in this release have had small values suppressed or randomised to protect confidentiality. As a result, sums of components may not add exactly to totals.
28 Calculations as shown in the commentary sections of this release are based on unrounded figures. Calculations using rounded figures may differ from those released. Where figures have been rounded in tables, discrepancies may occur between sums of component items and totals.
29 Other ABS products which may be of interest to users include:
ADDITIONAL STATISTICS AVAILABLE
30 The abridged life tables in chapter 4 are also available as a data cube (in Microsoft Excel format) available for download from the ABS website in Life Tables for Aboriginal and Torres Strait Islander Australians, 2015-2017 (cat. no. 3302.0.55.003):
31 Additional demographic information is available on the ABS website <https://www.abs.gov.au>; click Statistics, then under People click on Aboriginal and Torres Strait Islander Peoples. Users can also access the full range of electronic ABS data from the ABS website.
32 As well as the statistics included in this and related releases, the ABS may have other relevant data available on request. Inquiries should be made to the National Information and Referral Service on 1300 135 070.
33 The ABS also issues a daily Release Advice on the website which details the products to be released in the week ahead.
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