Understanding Population Statistics
There are two ways the Australian Bureau of Statistics (ABS) determines the size and characteristics of the population: the five-yearly Census and quarterly estimates of the resident population.
Every five years the ABS conducts the Census of Population and Housing. The Census results are released as two types of population counts:
- Census count based on usual residence
- Census count based on place of enumeration.
Also available from the Census are results by counts of:
- working population
Census counts: place of enumeration versus place of usual residence
The Census attempts to count every person in Australia on Census night. This includes people on vessels in or between Australian ports, or on long-distance trains, buses or aircraft. It also includes people entering Australia from overseas before midnight on Census night and Australian residents located in Antarctica.
The Census count by place of enumeration is a count of every person based on where they are located on Census night. In some cases, this is the same place as where they live; in other cases, people are counted away from home.
The Census count based on usual residence is a count of people based on the place where they usually live. This information is determined from responses to the question of usual residence on the Census form. The number of visitors to an area is not included in the usual residence Census count.
In popular holiday destinations the Census counts based on place of enumeration are normally larger than the Census counts based on usual residence. For example, there were 520,686 people enumerated in Gold Coast City local government area on Census night, of which only 494,501 were usual residents.
Estimated resident population
The estimated resident population (ERP) figure is the official population estimate published by the ABS, and represents the best possible estimate of the resident population.
ERP for each state and territory is updated quarterly using births, deaths, and overseas and interstate migration data until the next Census data are available. For sub-state geographies, estimated resident population figures are updated annually using a model which includes administrative data that indicate population change, such as dwelling approvals, Medicare enrolments and electoral enrolments.
Initially, all estimates of resident population are released as preliminary figures, designated (p). Subsequently, the figures are revised and designated (r). Estimated resident population figures prepared between Census dates are revised using the most recent Census data. These are called the ‘rebased’ estimates.
Determining estimated resident population figures from a Census count
Estimated resident population figures in the Census year are based on Census usual resident counts. Table 1 outlines the process for the preparation of Queensland’s preliminary ERP for the 2011 Census year.
Once a Census count based on usual residence is determined, an estimation of Census undercount and residents temporarily overseas, plus other smaller factors, are added to calculate Queensland’s estimated resident population at 9 August 2011 (the date of the 2011 Census). This estimate is then adjusted back to arrive at an estimate for 30 June to account for those who were born, those who died, and those who moved into or out of the state during the period from 1 July 2011 to 9 August 2011.
Table 1 Adjustment components of estimated resident population, Queensland, preliminary, 30 June 2011
|Components at 9 August 2011||Persons (’000)|
|Census count, actual location||4,457.9|
|plus - residents absent interstate||45.9|
|less - interstate visitors||105.2|
|less - overseas visitors||65.8|
|equals - Census count, place of usual residence||4,332.7|
|plus - allowance for undercount (a)||77.2|
|plus - demographic adjustment (a)||0.4|
|plus - residents temporarily overseas (a)||71.5|
|equals - estimated resident population at 9 August 2011||4,481.9|
|Backdating components to 30 June 2011|
|less ‑ births (a)||6.7|
|plus ‑ deaths (a)||3.3|
|less ‑ net interstate migration (a)||1.2|
|less ‑ net overseas migration (a)||3.3|
|equals - preliminary estimated resident population at 30 June 2011||4,474.1|
(a) These estimates are preliminary and may change in compilation of final rebased estimates.
Source: ABS 3101.0 Australian Demographic Statistics, Dec 2011
Difference between Census counts and estimated resident population
Compared with the estimated resident population figures, the Census count based on place of usual residence does not include people who did not fill out a Census form, and people temporarily overseas on Census night, and therefore not required to fill out a Census form. Some further differences may appear if significant change has occurred in the population and the process for estimating the resident population did not accurately reflect these changes.
When an estimated resident population figure is compared with a Census count based on place of enumeration, differences are likely to appear if there were visitors present in the area and if any usual residents were away from the area on Census night.
Table 2 provides a summary of population estimates available.
Table 2 Types of population estimates
|Name of population estimate||Coverage||Reference date|
|Census count: place of enumeration||A count of every person located in an area on Census night, including visitors.||Census night date|
|Census count: usual residence (UR)||A count of every person who usually lives in an area on Census night, excluding visitors.||Census night date|
|Estimated resident population (ERP): Census year||Official estimate of the population based on Census counts of usual residents that are adjusted to account for usual residents missed in the Census. These estimates are considered final.||30 June of the Census year|
|Estimated resident population (ERP): non-Census year||Official estimate of the population based on the previous Census year ERP. These estimates are considered preliminary and are subject to ongoing revision. Final ERPs for the intercensal period are established after the next Census.||Quarterly at the national, state and territory level
Annually (30 June) at the sub-state level
Other counts available from the Census
Estimated working population
The Census count of the working population includes all people who were employed in the week prior to the Census. Responses to the Census question concerning location of workplace are used to determine the number of people working in particular locations. Along with information on how these people travelled to work, these counts are important in planning for services for the daytime populations of employment locations and for transport planning.
Number of families versus number of households
A family is defined by the ABS as two or more people, with one person aged 15 years or more, who are related by blood, marriage (registered or de facto), adoption or fostering or in a stepfamily relationship and who are usually resident in the same household. In contrast, a household is defined by the ABS as one person or two or more related or unrelated persons who usually live in the same private dwelling. The basis of a family then is either a couple relationship, a lone parent–child relationship or other blood relationship. Thus it is possible for more than one family to live in the same household and for non-family members to be household members. A non-family household is either a lone-person household or a group household. All other households are made up of different family compositions.
Number of visitors in an area
People who are visiting Australia at the time of the Census are counted regardless of how long they have been in the country or how long they plan to stay.
Since the 2001 Census, overseas visitors were those people who said they would be usually resident in Australia for less than one year. In earlier Censuses, overseas visitors were those who said they would be usually resident in Australia for less than six months. The number of visitors from within Australia is separately identified in Census data and a range of characteristics can be provided for these visitors. In contrast, the only data for overseas visitors are age, sex and marital status.
- ABS 2901.0 2001 Census Dictionary
- ABS 2901.0 2006 Census Dictionary
- ABS 2901.0 2011 Census Dictionary
- ABS 3101.0 Australian Demographic Statistics, Dec 2011
- ABS 2914.0.55.002 2006 Census of Population and Housing: Media Releases and Fact Sheets, 2006, ‘The difference explained: comparing the Census population count and the estimated resident population’
For further information contact OESR.
Visit the Australian Bureau of Statistics website to obtain census counts or the latest estimated resident population figures.
The December quarter 2011 issue of Australian Demographic Statistics (ABS 3101.0) features an article, Preliminary Rebasing of Australia's Population Estimates using the 2011 Census of Population and Housing.
A description of the range of population estimates, and their scheduled release dates, available following the 2011 Census rebasing cycle can be found in Information Paper: Rebasing Population Estimates, Australia, 2011 (ABS 3101.0.55.001).
A detailed description of the concepts, sources and methods used by the ABS in the production of population estimates can be found in Population Estimates: Concepts, Sources and Methods, 2009 (ABS 3228.0.55.001). Additional information on population concepts can be found in Information Paper: Population Concepts, 2008 (ABS 3107.0.55.006).
Information about the future of population estimates under the new statistical geography standard can be found in Information Paper: Population Estimates under Australia’s New Statistical Geography (ABS 3219.0.55.001).
Last reviewed 2 August 2012