TECHNICAL NOTES
Different types of population counts
The estimated resident population (ERP) is Australia's official population measure. It is based on Census counts of usual residents (discussed below), which are adjusted for undercount in the Census and for the number of Australian residents estimated to have been temporarily overseas at the time of the Census. Further adjustments are made for births, deaths and net migration in the period from the date of the estimate (30 June) to Census Night (that is, 9 August 2011).
As they are the most accurate count of the population, ERP figures have been used wherever possible in the article '100 Years of Census Lives - Population'. However, only a limited number of characteristics of the population are available through ERP: age, sex, marital status (registered), country of birth and geographic location. To allow analysis of the broad range of characteristics available from the Census, two different population counts from the Census have been used in 'Reflecting a Nation: Stories from the 2011 Census' - place of enumeration and place of usual residence.
In Australia, the Census counts people where they are located on Census Night - their ‘place of enumeration’. The place of enumeration Census count is used where comparisons are made with Censuses prior to 1976, as this was the only Census count available from earlier Censuses. It will also be used where the analysis specifically examines the population counted on Census Night, rather than where people are usually resident.
The usual resident population count is derived from information people provide on their Census form about where they lived, or intended to live, for 6 months or more in 2011 - their ‘place of usual residence’. Information about people who are not at home on Census Night is linked back to the area in which they usually live (that is, their - Statistical Area 1). However, it is impractical to link the information about these people back to their actual families, households or dwellings. In some instances, the absence of this information could have an impact on the analysis of the characteristics of families, households and dwellings.
As Census usual resident population counts are the most common population count used in these articles, their use in tables, graphs and text is not noted. Where place of enumeration population counts are used, this is noted in footnotes and in the text.
Time series comparisons
In a number of articles comparisons have been made between the 2011 Census and earlier Censuses. A number of significant events affecting the Census have occurred that should be considered when making comparisons of Census data over time.
Firstly, under the constitution at Federation, ‘Aboriginal natives’ were not to be counted in official population figures and so were excluded from the final Census results. This restriction was removed following a referendum in 1967. The Australian Bureau of Statistics has endeavoured to conduct as full a count of Aboriginal and Torres Strait Islander peoples as possible from the 1971 Census onwards.
Secondly, the 1976 Census results are based on a sample of half of the forms received from private dwellings, which have been weighted to represent a full count of the population. This was done because of budgetary constraints introduced by the government at the time of processing the forms. Exceptions were in the Northern Territory, where all of the forms from private dwellings were processed, as well as all forms from non-private dwellings across Australia.
In most cases, the classifications used to make comparisons over time are the same in each Census year and the comparisons have been made with a high degree of certainty. In other cases, the classifications and/or processing methods have changed over time and the comparisons are less certain. Comparisons have only been made where the data have been assessed as fit for the purpose for which they are used: in some instances, changes over time have not been discussed because of the degree of uncertainty and change involved.
While the 2011 Census was conducted on a similar basis to the 2006 Census there have been a number of changes to the 2011 classifications. For a summary of changes please see the 'What's New for 2011?' section in the Census Dictionary, 2011 (cat. no. 2901.0).
Totals - rounding and data perturbation
Figures have been rounded in all articles. Therefore, discrepancies may occur between the sums of the component items and totals.
A range of methods have been used to protect the confidentiality of respondents when data are released from the Census. This produces minor variations in the data that may result in totals not being equal in all tables and quoted numbers.
Treatment of particular data items
To be as consistent as possible with ERP figures and to minimise the effect of variations in the numbers of overseas visitors on time series data, all overseas visitors have been excluded from data used in the report, unless otherwise specified.
Where classifications used included a ‘not stated’ category, data in this category have been excluded prior to the calculation of percentages - in effect, this has ‘distributed’ those results across the remaining categories. The only exception to this is for the Religious Affiliation classification, where ‘not stated’ is an accepted response. Column or row totals for counts in all tables, including tables showing percentages, have the number of ‘not stated’ responses included in the total. Where the number of responses in a ‘not stated’ category may have had an impact on the information presented, this is noted in footnotes and in the text. In some instances, data have not been analysed because of large numbers of ‘not stated’ responses.
Where classifications used included an ‘inadequately described’ or similar category, data in these categories were generally treated as a standard category unless otherwise stated.
Symbols and usages
The following symbols and usages mean:
 | % | per cent |
| . . | not applicable |
| n.a. | not available |
| no. | number |
| $ | dollar |
| '000 | thousand |
Australia, states and territories of Australia
| Aust. | Australia |
| NSW | New South Wales |
| Vic. | Victoria |
| Qld | Queensland |
| SA | South Australia |
| WA | Western Australia |
| Tas. | Tasmania |
| NT | Northern Territory |
| ACT | Australian Capital Territory |
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