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3238.0.55.001 - Estimates of Aboriginal and Torres Strait Islander Australians, June 2011 Quality Declaration 
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 30/08/2013   
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EXPLANATORY NOTES


INTRODUCTION

1 This publication contains final estimates of the Aboriginal and Torres Strait Islander, non-Indigenous and total populations of Australia at 30 June 2011, based on results of the 2011 Census of Population and Housing.

2 Estimates are disaggregated by age and sex for states/territories, Remoteness Areas and Indigenous Regions. Only total estimates for Statistical Areas Level 2 are available.


ESTIMATED RESIDENT POPULATION

3 Estimated resident population (ERP) is the official measure of the population of Australia, based on the concept of usual residence within Australia. Usual residence is that place where each person has lived or intends to live for six months or more from the reference date for data collection.

4 The estimates of the Aboriginal and Torres Strait Islander population presented in this publication are based on 2011 Census of Population and Housing counts of Aboriginal and Torres Strait Islander Australians, adjusted for net undercount as measured by the Post Enumeration Survey. The extent of undercoverage of Aboriginal and Torres Strait Islander Australians in the 2011 Census and the relatively small sample size of the Post Enumeration Survey to adjust for that undercoverage means the estimates should be interpreted with a degree of caution. For more information on data quality see the relevant section of this Explanatory Note and Technical Note: Estimated Aboriginal and Torres Strait Islander Australian Resident Population - Method of Calculation.


INDIGENOUS STATUS

5 The Aboriginal and Torres Strait Islander population of Australia comprises people who are of Aboriginal origin, Torres Strait Islander origin or both Aboriginal and Torres Strait Islander origin. The Commonwealth definition of an Aboriginal and/or Torres Strait Islander person is:

  • a person of Aboriginal or Torres Strait Islander descent who;
  • identifies as being of Aboriginal or Torres Strait Islander origin and who is;
  • accepted as such by the community with which the person associates.

6 The 2011 Census of Population and Housing (Household Form) asked the following question of each person:
Graphic: Indigenous Status question from the 2011 Census


METHOD OF ESTIMATION

7 Estimated resident populations by Indigenous status are compiled using Census, Post Enumeration Survey (PES) and other demographic information. Starting with Census counts by place of usual residence, a number of steps are involved. These include:
  • Imputation of Indigenous status for Census records with unknown Indigenous status (as a result of either non-response to the Aboriginal and Torres Strait Islander origin question in the Census, or unknown Indigenous status on Census records imputed by the Australian Bureau of Statistics (ABS) when a form could not be obtained from occupied dwellings identified in the field);
  • An allowance for net Census undercount: in a complex exercise such as the Census, it is inevitable that some people will be missed and some will be included more than once. The PES, conducted shortly after Census night, collects information about where people were on Census night and their characteristics to estimate net Census undercount;
  • An estimate of the number of Australian residents temporarily overseas at the time of the Census;
  • Backdating from the Census date of 9 August 2011 to the ERP reference date of 30 June 2011 using data on births, deaths, and interstate and overseas migration for the intervening period;
  • Minor demographic adjustments designed to address any anomalies in age and sex composition.

8 For further information, see Technical Note: Estimated Resident Aboriginal and Torres Strait Islander Australian Population - Method of Calculation.


DATA QUALITY

Census

9 The ABS aims to produce high quality data from the Census. To achieve this, extensive effort is put into Census form design, collection procedures, and processing procedures. There are four principle sources of error in Census data: partial response, processing error, respondent error and undercount.

10 Partial response: When completing their Census form, some people do not answer all the questions which apply to them. While questions of a sensitive nature are generally excluded from the Census, all topics have a level of non-response. However, this level can be measured and is generally low. In those instances where a householder fails to answer a question, a not stated code is allocated during processing, with the exception of non-response to age, sex, marital status and place of usual residence. These variables are needed for population estimates, so they are imputed using other information on the Census form, as well as aggregate data from the previous Census.

11 Processing error: The processing of information from Census forms is mostly automated, using scanning, Intelligent Character Recognition and other automatic processes. Quality assurance procedures are used during Census processing to ensure processing errors are kept at an acceptable level. Sample checking is undertaken during coding operations, and corrections are made where necessary.

12 Respondent error: The Census form may be completed by one household member on behalf of others. Incorrect answers can be introduced to the Census form if the respondent does not understand the question or does not know the correct information about other household members. Many of these errors remain in the final data.

13 Undercount: 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, but it is inevitable that a small number of people will be missed, some will be counted more than once and some will not be identified correctly. In Australia, more people are missed from the Census than are counted more than once. The net effect when both factors are taken into account is an undercount.

14 Each of these sources of error are particularly relevant to, and have the potential to significantly impact on, the Census counts of Aboriginal and Torres Strait Islander Australians.

15 Further information on Census data quality is available in Census Dictionary, 2011 (cat. no. 2901.0) and 2011 Census Data Quality Working Papers, available on the ABS web site www.abs.gov.au/census.


The Post Enumeration Survey (PES), sampling error and undercount

16 Due to the uncertainty in Aboriginal and Torres Strait Islander Census counts as well as the estimation of net undercount of the Aboriginal and Torres Strait Islander population, estimates presented in this product should be interpreted with a degree of caution.

17 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. The design of the survey is such that estimates of net undercount are suitable for augmenting Census counts for the purpose of deriving population estimates for Australia and the states and territories. For 2011, the survey had a sample size of around 43,000 households across Australia.

18 As estimates of undercount are based on a sample survey they are subject to sampling error. Since only a sample of dwellings is included in the PES, estimates derived from the survey may differ from figures which would have been obtained if all dwellings had been included in the survey. One measure of the likely difference is given by the standard error (SE) which indicates the extent to which an estimate might have varied by chance because only a sample was included. The relative standard error (RSE) is the standard error expressed as a percentage of the estimate to which it refers.

19 For Australia, the direct estimate of the Aboriginal and Torres Strait Islander population obtained from the PES was 662,300 persons, with a standard error of 14,300 (and a relative standard error (RSE) of 2.2%). For estimating the Aboriginal and Torres Strait Islander population of states and territories, undercount estimates were adjusted to improve the reliability of estimates. For more information on the method applied, see Technical Note: Estimated Resident Aboriginal and Torres Strait Islander Australian Population - Method of Calculation. Unadjusted undercount rates are presented below but should be used for illustrative purposes only. The adjusted estimates which were actually used in the calculation of final Aboriginal and Torres Strait Islander population estimates and which should be used can be found in Technical Note: Estimated Resident Aboriginal and Torres Strait Islander Australian Population - Method of Calculation.

20

Unadjusted PES undercount estimates, states and territories - 2011(a)

Net undercount
SE
Net undercount rate
SE
no.
no.
%
%

New South Wales
26 388
9 132
13.3
4.0
Victoria
12 395
4 781
24.6
7.2
Queensland
34 815
8 231
18.3
3.5
South Australia
6 852
1 977
18.4
4.3
Western Australia
17 340
4 493
19.9
4.1
Tasmania
5 140
1 632
20.8
5.2
Northern Territory
11 043
2 053
16.3
2.5
Australian Capital Territory
216
775
4.0
13.8

(a) For illustrative purposes only. See Explanatory Note 19.


21 The PES sample is insufficient to produce estimates of net undercount by Indigenous status at the sub-state/territory level. Undercount was therefore apportioned to Statistical Areas Level 2 based on age, sex, Indigenous status and state/territory. For further information on this process, please refer to Regional Population Grow, Australia, 2011 (cat. no. 3218.0)

22 It is important to note that at the sub-state/territory level, differences between Census counts and estimates of the Aboriginal and Torres Strait Islander population should not be interpreted as a definitive measure of the actual level of undercount; rather, these differences are a by-product of the assumptions that contribute to the estimation process, and the differences should be considered indicative, based on the best available (though limited) information.

23 For further information see Technical Note: Estimated Resident Aboriginal and Torres Strait Islander Australian Population - Method of Calculation.

24 For further information on the Post Enumeration Survey see Census of Population and Housing - Details of Undercount, 2011 (cat. no. 2940.0).


AUSTRALIAN STATISTICAL AREAS

25 This publication contains data coded to a number of statistical geographic structures within the statistical geography classification called the Australian Statistical Geography Standard (ASGS). The structures used are: the Main Structure, the Remoteness Structure and the Indigenous Structure.

26 Users should note that the Australian Statistical Geography Standard (ASGS) became effective in July 2011. It replaces the previously used Australian Standard Geographical classification (ASGC) and differs in the fact that the ASGS is more stable, the regions are more consistent in population size, are designed to give the maximum geographical detail for a range of published data, and represent underlying settlement patterns and socio-economic relationships. Information on the new standard is available on the ABS website under 'Statistical Geography'. Alternatively, see Volume 1 - Main Structure and Greater Capital City Statistical Areas, July 2011 (cat. no. 1270.0.55.001).


Australian Standard Geographical Structure - Main Structure

27 The ABS Structures are a hierarchy of regions developed for the release of particular ABS statistics. Their components are described below:
  • Mesh Blocks (MBs): are the smallest geographical region in the ASGS. There are approximately 347,000 covering the whole of Australia. They broadly identify land use such as: residential, commercial, agriculture and parks etc. Mesh Blocks are very small and are the building blocks for all the larger regions of the ASGS. Only limited Census data (total population and dwelling counts) are released at the Mesh Block level.
  • Statistical Areas Level 1 (SA1s): have been designed as the smallest unit for the release of Census data. SA1s generally have a population of 200 to 800 persons, and an average population of about 400 persons. They are built from whole Mesh Blocks and there are approximately 55,000 SA1s covering the whole of Australia.
  • Statistical Areas Level 2 (SA2s): are a general-purpose medium sized area built from whole SA1s. Their aim is to represent a community that interacts together socially and economically. SA2s generally have a population range of 3,000 to 25,000 persons , and have an average population of about 10,000 persons. The SA2 is the lowest level of the ASGS structure for which Estimated Resident Population (ERP), Health and Vitals and other non-Census ABS data are generally available. There are about 2,200 SA2s covering the whole of Australia.
  • Statistical Areas Level 3 (SA3s): provide a standardised regional breakup of Australia. The aim of SA3s is to create a standard framework for the analysis of ABS data at the regional level through clustering groups of SA2s that have similar regional characteristics. SA3s are built from whole SA2s and in general have populations between 30,000 to 130,000. They are often the functional areas of regional cities and large urban transport and service hubs.
  • Statistical Areas Level 4 (SA4s): are the largest sub-State regions in the Main Structure. They are designed for the output of Labour Force Survey data and reflect labour markets within each state and territory. SA4s are built from whole SA3s and cover the whole of Australia. There are 88 SA4s.

28 For the purposes of this publication, Jervis Bay Territory, Christmas Island and Cocos (Keeling) Islands are collectively referred to as 'Other Territories' and are included in the totals for Australia.

29 For further information see Australian Statistical Geography Standard (ASGS): Volume 1 - Main Structure and Greater Capital City Statistical Areas, July 2011 (cat. no. 1270.0.55.001).


Remoteness Structure

30 The purpose of the Remoteness Structure is to divide Australia into broad geographic regions that share common characteristics of remoteness for statistical purposes. The Remoteness Structure divides each state and territory into several regions on the basis of their relative access to services. Remoteness Areas (RAs) are the spatial units that make up the ASGS Remoteness Structure. There are six classes of RA in the Remoteness Structure: Major Cities of Australia, Inner Regional Australia, Outer Regional Australia, Remote Australia, Very Remote Australia and Migratory.

31 Within each state/territory, each RA represents an aggregation of non-contiguous geographical areas which share common characteristics of remoteness (constructed from SA1s). 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 each state/territory.

32 For further information see Australian Statistical Geography Standard (ASGS): Volume 5 - Remoteness Structure, July 2011 (cat. no. 1270.0.55.005).


Indigenous Geography Structure

33 Data are also presented according to the Indigenous Structure of the Australian Statistical Geography Standard (ASGS). Under this classification, areas are defined as follows:
  • Indigenous Locations (ILOCs): are aggregates of one or more SA1s. ILOCs generally represent small Aboriginal and Torres Strait Islander communities with a minimum population of 90 Aboriginal and Torres Strait Islander usual residents. An ILOC is an area designed to allow the production of Census statistics relating to Aboriginal and Torres Strait Islander people with a high level of spatial accuracy while maintaining the confidentiality of individuals. For the 2011 Census, 1116 ILOCs have been defined to cover the whole of geographic Australia.
  • Indigenous Areas (IAREs): are medium sized geographical units designed to facilitate the release of more detailed statistics. IAREs provide a balance between spatial resolution and increased granularity of attribute data. They are created by aggregating one or more ILOCs. For the 2011 Census, 429 IAREs are defined to cover the whole of geographic Australia.
  • 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 IAREs. The greater population of IREGs enables the highest level of granularity of attribute data through greater cross classification of variables compared with IAREs and ILOCs. For the 2011 Census 57 IREGs are defined to cover the whole of geographic Australia. IREGs do not cross state or territory borders.

34 For further information see Australian Statistical Geography Standard (ASGS): Volume 2 - Indigenous Structure, July 2011 (cat. no. 1270.0.55.002).


CONFIDENTIALITY

35 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 that identifiable information about individual respondents cannot be derived from published data.

36 To protect confidentiality within this publication, some small cell values have been suppressed.

37 In addition, some Remoteness Areas in the states and territories have been combined to protect confidentiality. In Victoria, Outer Regional Australia and Remote Australia have been combined to produce Rest of Victoria. In Tasmania, Remote Australia, and Very Remote Australia have been combined to produce Rest of Tasmania. Remoteness Areas are not available for the ACT in this product.


FURTHER INFORMATION

Related publications and references

38 Other ABS publications that may be of interest to users of this publication include:
39 Current publications and other products released by the ABS are listed on the ABS web site www.abs.gov.au.

40 As well as the statistics included in this and related publications, additional information is available from the ABS web site at www.abs.gov.au and accessing Themes/Demography.


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