Estimates and Projections, Aboriginal and Torres Strait Islander Australians methodology

The birth of a live-born child where either the mother or the father was identified as being of Aboriginal or Torres Strait Islander origin on the birth registration form.

Registration of deaths is the responsibility of the state and territory Registries of Births, Deaths and Marriages. Information about the deceased is acquired from a Death Registration Form (DRF). All states and territories use information from DRF to identify an Aboriginal and Torres Strait Islander death.

In addition, some states and territories also use the Medical Certificate of Cause of Death (MCCD) to identify an Aboriginal and Torres Strait Islander death. In 2007, the MCCD was introduced in South Australia, Western Australia, Tasmania, the Northern Territory and the Australian Capital Territory. The Queensland Registry of Births, Deaths and Marriages introduced the MCCD in 2015. This resulted in a noticeable decrease in the number of deaths for which the Indigenous status was 'not stated' and an increase in the number of deaths identified as Aboriginal and Torres Strait Islander in Queensland. If the Indigenous status reported in the DRF does not agree with that in the MCCD, an identification from either source that the deceased was an Aboriginal and/or Torres Strait Islander person is given preference over non-Indigenous.

The phenomenon of uneven population age distribution in Census or survey data. When age heaping occurs, data show systematic spikes on particular ages such as those ending in 0 or 5. This happens as a result of 'digit preference' or rounding when respondents are unsure of their age or the age of others they are reporting on behalf of. An age heaping adjustment was applied to the population of the Northern Territory, as part of compiling the final 30 June 2016 ERP based on the 2016 Census.

A bar chart graphically representing the age structure of the population, usually in five-year age groups, for males and females separately. The age structure of the population usually approximates the shape of a pyramid because mortality progressively reduces the number in each birth cohort as it ages. The age pyramid is useful to show the existence of unusually large or small cohorts, and in this way, not only conveys information about a country's past demographic history, but also a great deal about its demographic future.

The number of deaths (either occurred or registered) during the calendar year at a specified age per 1,000 of the estimated resident population of the same age at the mid-point of the year (30 June). Pro rata adjustment is made in respect of deaths for which the age of the deceased is not given.

The number of live births (either occurred or registered) during the calendar year, according to the age of the mother, per 1,000 of the female estimated resident population of the same age at 30 June. In the calculation of these rates, births to mothers under 15 years are included in the 15-19 years age group, and births to mothers aged 50 years and over are included in the 45-49 years age group. Pro rata adjustment is made for births for which the age of the mother is not given.

The number of live births (either occurred or registered) during the calendar year, according to the age of the father, per 1,000 of the male estimated resident population of the same age at 30 June. In the calculation of these rates, births to fathers under 15 years are included in the 15-19 years age group, and births to fathers aged 50 years and over are included in the 45-49 years age group. Pro rata adjustment is made for births for which the age of the father is not given.

The delivery of a child, irrespective of the duration of pregnancy, who, after being born, breathes or shows any evidence of life such as heartbeat.

Completed fertility represents the average number of births a cohort of females have borne over their reproductive lifetimes.

The permanent disappearance of all evidence of life after birth has taken place. The definition excludes all deaths prior to live birth. For the purposes of the ABS Death Registration collection, a death refers to any death which occurs in, or en route to Australia and is registered with a state or territory Registry of Births, Deaths and Marriages.

The official measure of the population of Australia is based on the concept of usual residence. It refers to all people, regardless of nationality, citizenship or legal status, who usually live in Australia, with the exception of foreign diplomatic personnel and their families. It includes usual residents who are overseas for less than 12 months over a 16 month period. It excludes overseas visitors who are in Australia for less than 12 months over a 16 month period.

Estimates of the Australian resident population are generated on a quarterly basis by adding natural increase (the excess of births over deaths) and net overseas migration (NOM) occurring during the period to the population at the beginning of each period.

Indigenous Regions (IREGs) are large geographical units loosely based on the former Aboriginal and Torres Strait Islander Commission boundaries. They are created by aggregating one or more Indigenous Areas.

The time period between 30 June in the previous Census year and 30 June of the latest Census year.

The average number of additional years a person of a given age and sex might expect to live if the age-specific death rates of each period continued throughout his/her lifetime.

A tabular, numerical representation of mortality and survivorship of a cohort of births at each age of life. The conventional life table is based on the assumption that as the cohort passes through life it experiences mortality at each age in accordance with a predetermined pattern (usually based upon death rates from a real population during a particular period of time) of mortality rates which do not change from year to year. The life table thus constitutes a hypothetical model of mortality, and it does not describe the actual mortality which characterises a cohort as it ages.

Life tables may be complete or abridged, depending on the age interval used in their compilation. Complete life tables such as those for the Australian population contain data by single years of age, while abridged life tables, such as those for the Aboriginal and Torres Strait Islander population, contain data for five-year age groups. Due to differences in mortality patterns between males and females at different ages, life tables are generally constructed separately for each sex.

For any distribution the median value is that which divides the relevant population into two equal parts, half falling below the value, and half exceeding it. Thus, the median age is the age at which half the population is older and half is younger.

The movement of people across a specified boundary for the purpose of establishing a new or semi-permanent residence. Migration can be international (migration between countries) and internal (migration within a country).

The difference in mortality when comparing one population group with another. In this release, it is calculated as the ratio of life expectancy at birth for a particular geographic region (e.g. state/territory) over the life expectancy at birth for Australia.

Excess of births over deaths.

Net interstate migration is the net gain or loss of population though interstate migration being the change of a person's place of usual residence from one state or territory to another state or territory.

Net overseas migration is the net gain or loss of population through immigration to Australia and emigration from Australia.

For Australia, net population growth is the sum of natural increase and net overseas migration. For the states and territories, net population growth also includes net interstate migration.

The difference between the actual Census count (including imputations) and an estimate of the number of people who should have been counted in the Census. This estimate is based on the Post Enumeration Survey (PES) conducted after each Census. For a category of person (e.g. based on age, sex and state of usual residence), net undercount is the resultant of Census undercount, overcount, misclassification and imputation error.

Following the 1992 amendments to the Acts Interpretation Act to include the Indian Ocean Territories of Christmas Island and the Cocos (Keeling) Islands as part of geographic Australia, another category of the state and territory level has been created, known as Other Territories. Other Territories include Jervis Bay Territory, previously included with the Australian Capital Territory, as well as Christmas Island, the Cocos (Keeling) Islands and Norfolk Island.

The Census Post Enumeration Survey (PES) is a household survey conducted following the Census. The PES allows the ABS to estimate the number of people missed in the Census and the number counted more than once or in error. Results from the PES contribute to a more accurate calculation of the estimated resident population (ERP) for Australia and the states and territories, which is then backdated to 30 June of the Census year.

An aggregation of non-continuous geographical areas which share common characteristics of remoteness. The delimitation criteria for Remoteness Areas (RAs) are based on the Accessibility/Remoteness Index of Australia (ARIA+) which measures the remoteness of a point based on the road distance to the nearest urban centre. The RA categories range from Major Cities to Very Remote. Within the Australian Statistical Geography Standard, each RA is created from a grouping of Statistical Areas Level 1 having a particular degree of remoteness.

The number of males per 100 females.

State or territory of usual residence refers to the state or territory of usual residence of:

• the population
• the mother (Birth Registrations collection) and
• the deceased (Death Registrations collection).
   

The sum of age-specific fertility rates expressed as rate per woman. It represents the number of children a female would bear during her lifetime if she experienced current age-specific fertility rates at each age of her reproductive life.

The sum of age-specific paternity rates expressed as a rate per man. It represents the number of children a male would father during his lifetime if he experienced current age-specific paternity rates at each age of his reproductive life.

The intercensal growth in the Aboriginal and Torres Strait Islander population counts that cannot be fully explained by births, deaths and migration.

Australian Bureau of Statistics (ABS) estimates and projections of the Aboriginal and Torres Strait Islander population of Australia are based on population estimates derived from the most recent Census of Population and Housing (currently 2016) and Post Enumeration Survey as well as data from the birth and death registration collections. Assumptions about past and future levels of the components of population change are applied to the base Census population in order to produce estimates (for earlier reference years) and projections (for future reference years).

Assumptions are derived from an analysis of data sourced form a variety of institutional environments. Much of this data is administrative by-product data collected by other organisations. Assumptions on fertility and mortality are based on births and deaths statistics extracted from registers administered by the various state and territory registrars of births, deaths and marriages.

For information on the institutional environment of the Australian Bureau of Statistics (ABS), including the legislative obligations of the ABS, financing and governance arrangements, and mechanisms for scrutiny of ABS operations, please see ABS Institutional Environment .

Aboriginal and Torres Strait Islander population estimates for years prior to the base population provide estimates on a temporally consistent basis, thus eliminating any inconsistencies in estimates due to the changing propensity of people to identify as Aboriginal and Torres Strait Islander across Censuses or changes to the methods used to collect this information. Estimates are published for Australia and the states/territories, by five-year age groups and sex. Single year of age data is also available for persons only.

Population projections inform on future changes in the Aboriginal and Torres Strait Islander population of Australia, such as population growth/decline and changes in age structure, and are therefore used in a variety of key planning decisions. Projections are published for Australia, states/territories, Indigenous Regions and three categories of Remoteness Areas, by five-year age groups and sex. Single year of age data is also available for Australia, states/territories and three categories of Remoteness Areas for persons only.

Assumptions have been formulated on the basis of past demographic trends, in conjunction with consultation with various experts and government department representatives at the national and state/territory level.

ABS Aboriginal and Torres Strait Islander population estimates and projections are compiled and published once every five years (i.e. after each Census of Population and Housing).

The estimates and projections presented in this release are based on results of the 2016 Census of Population and Housing, adjusted for net undercount as measured by the Post Enumeration Survey (PES). The goal of the Census is to obtain a complete measure of the number, and characteristics, of people in Australia on Census night and their dwellings.

The ABS conducts the PES shortly after the Census to determine how many people were missed in the Census and how many were counted more than once. For 2016, the net undercount of the Aboriginal and Torres Strait Islander population was 137,750 persons (17.5%). The extent of undercoverage of Aboriginal and Torres Strait Islander Australians in the 2016 Census, the relatively small sample size of the PES to adjust for the undercoverage, and the number of records with unknown Indigenous status means that 2016 population estimates should be interpreted with caution. For more information see Estimates of Aboriginal and Torres Strait Islander Australians, June 2016 (cat. no. 3238.0.55.001).

It is important to remember that while the Census, PES and other administrative datasets used in compiling these estimates produce statistics with relatively small amounts of error, this error can be more significant when focussing on a very small population (like the Aboriginal and Torres Strait Islander population).

Given that the quality of historical Aboriginal and Torres Strait Islander component data (births, deaths and migration) is variable, ABS Aboriginal and Torres Strait Islander population estimates for non-Census years are produced by applying assumptions about past levels of Aboriginal and Torres Strait Islander life expectancy and net interstate migration at birth to the population. As levels of life expectancy at birth are unknown, estimates should be treated with caution, particularly for the period 2001 to 2005.

Aboriginal and Torres Strait Islander population estimates for 2001 to 2015 based on the 2016 Census supersede previously published estimates for this period.

ABS Aboriginal and Torres Strait Islander population projections are based on a number of assumptions on future levels of fertility, mortality and migration. They are not intended as predictions or forecasts, but are illustrative of growth and change in the Aboriginal and Torres Strait Islander population that would occur if the assumptions were to prevail over the projection period.

While the assumptions are formulated on the basis of an assessment of past demographic trends, there is no certainty that any of the assumptions will be realised. In addition, the assumptions do not attempt to allow for non-demographic factors (such as major government policy decisions, economic factors, natural disasters, epidemics or significant health treatment improvements) which may affect future demographic behaviour or outcomes.

The accuracy of each component of the data presented in this release is also affected by changing social norms and an individual's propensity to identify as an Aboriginal and Torres Strait Islander Australian. This propensity is not only affected by an individual's decision on how they choose to identify, but also by improvements to collections methods that allow the data to be captured more accurately. This propensity can change over time and between collections, which can significantly affect the accuracy of the data.

The estimates and projections presented in this release are not consistent with estimates and projections based on 2011 or previous Censuses. As the assumptions used in each successive set of Aboriginal and Torres Strait Islander population estimates and projections incorporate recent trends, comparison of data across issues of this release is not advised. As mentioned above, the coherence of this data is also affected an individual's propensity to identify in each collection and the ability of each dataset to accurately capture this information which can vary across time and between data sources. The coherence between the estimates and projections compiled at different points in time is explored in more detail on the page: Guide to using historical estimates for comparative analysis and reporting.

ABS population projections are not intended as predictions or forecasts, and should not be considered as such. Rather, they are illustrations of growth and change in the population that would occur if the assumptions were to prevail over the projection period.

This release contains information about the assumptions and methods used to produce the Aboriginal and Torres Strait Islander population estimates and projections. It also contains Explanatory Notes and Glossary that provide information on the data sources, terminology, classifications and other technical aspects associated with these statistics and their use.

ABS Aboriginal and Torres Strait Islander population projections are available in a variety of formats on the ABS web site under the 3238.0 product family. The formats available are:

• Main Features, which contains commentary on key figures
• Datacubes (in excel and ABS.Stat formats) containing:
   
  • Aboriginal and Torres Strait Islander population estimates and projections for Australia and the states and territories, by five-year age groups to 85 years and over (65 years and over for Tasmania and the Australian Capital Territory), and sex, for all projection series ( Series A-I);
  • Aboriginal and Torres Strait Islander population projections for Indigenous Regions, by five-year age groups (to 65 years and over) and sex (Series A, B and C);
  • Aboriginal and Torres Strait Islander population projections for Remoteness Areas, by five-year age groups (to 75 years and over) and sex (Series A, B and C).
  • data cubes containing Aboriginal and Torres Strait Islander population projections, components of change and summary statistics for Australia and the states and territories, Indigenous Regions and Remoteness Areas, for the three main projection series (Series A, B and C).
     

If the information you require is not available as a standard product, then ABS Consultancy Services can help you with customised services to suit your needs. For inquiries contact the National Information Referral Service on 1300 135 070 or email client.services@abs.gov.au.

The ABS observes strict confidentiality protocols as required by the Census and Statistics Act, 1905. This may limit access to data at a detailed level.

ABS and AIHW 2012, The Health and Welfare of Australia's Aboriginal and Torres Strait Islander Peoples, cat. no. 4704.0, ABS, Canberra.

ABS 2014, Estimates and Projections, Aboriginal and Torres Strait Islander Australians, 2001 to 2026, cat. no. 3238.0. ABS, Canberra.

ABS 2018, Census of Population and Housing: Understanding the Increase in Aboriginal and Torres Strait Islander Counts, 2016, cat. no. 2077.0, ABS, Canberra.

ABS 2018, Estimates of Aboriginal and Torres Strait Islander Australians, June 2016, cat. no. 3238.0.55.001, ABS, Canberra.

ABS 2018, Life Tables for Aboriginal and Torres Strait Islander Australians, 2015-2017, cat. no. 3302.0.55.003, ABS, Canberra.

ABS 2018, Population Projections, Australia, 2017 (base) - 2066, cat. no. 3222.0, ABS, Canberra.

ABS various years, Births, Australia, cat. no. 3301.0, ABS, Canberra

ABS various years, Deaths, Australia, cat. no. 3302.0, ABS, Canberra.

Wilson T, Condon JR and Barnes T 2007, Northern Territory Indigenous Life Expectancy Improvements, 1967-2004, Australian and New Zealand Journal of Public Health, vol. 31, no. 2, pp 184-8.