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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.

Census

Every five years the ABS conducts the Census of Population and Housing. The census results are released as two types of population counts:

Also available from the Census are results by counts of:

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 final 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, final, 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 2.6
   plus - residents temporarily overseas 73.3
   equals - estimated resident population at 9 August 2011 4,485.8
   
Backdating components to 30 June 2011
   less ‑ births (b) 6.7
   plus ‑ deaths (b) 3.4
   less ‑ net interstate migration (b) 1.2
   less ‑ net overseas migration (b) 4.5
   equals - final estimated resident population at 30 June 2011 4,476.8

(a) Includes Census net undercount from the 2011 Post Enumeration Survey and minor adjustments to address additional data coherence and quality matters.

(b) Component data calculated for the period 1 July to 9 August 2011.

Source: ABS 3101.0 Australian Demographic Statistics, Dec 2012

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.

References

Further information

For further information contact Queensland Government Statistician's Office.

Visit the Australian Bureau of Statistics website to obtain census counts or the latest estimated resident population figures.

Suggested reading

The December quarter 2012 issue of Australian Demographic Statistics (ABS 3101.0) features an article, Final Rebasing of Australia's Population Estimates, September Quarter 2006 – June Quarter 2011.

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 1 June 2016