Census counts and Estimated Resident Population explained!
With the majority of 2001 Census data now available, it is opportune to explain the difference between census counts and estimated resident population.
A census count includes every person who spent census night in Australia, except diplomats and their families. These counts are released on two different bases: place of enumeration and place of usual residence.
Much of the information contained in census products and services is based on the place of enumeration. This means people were counted according to where they were actually staying on census night, 7 August 2001, as opposed to where they normally live. Information for this count is available for Collection Districts (CDs), a CD being approximately 225 households, and aggregates of CDs. Holiday resort areas such as the snowfields or the Gold Coast may, for example, show a large enumeration count on census night compared with the usual residence count for that area.
Census counts at place of usual residence are based on where people usually live. The 2001 Census is the first census where usual residence data will be available at CD level. Previously, place of usual residence was only coded to Statistical Local Area (SLA) level. SLAs consist of one or more CDs. Census counts compiled on this basis are less likely to be influenced by seasonal factors such as school holidays.
The Estimated Resident Population (ERP) is the ABS' official estimate of the population and is based on the concept of residence. It refers to all people, regardless of nationality or citizenship, who usually live in Australia, with the exception of foreign diplomatic personnel and their families. It includes usual residents of Australia who are overseas for less than 12 months and excludes overseas visitors who are in Australia for less than 12 months.
The ERP is obtained for the census date (7 August 2001), and is based on census counts by place of usual residence. Added to this figure are the estimated net census undercount and Australian residents estimated to have been temporarily overseas at the time of the Census. Overseas visitors in Australia are excluded from this calculation.
This ERP is back dated to 30 June of the Census year by adjusting for the number of births, deaths and overseas and interstate migration from 1 July to the census date.
After each census, estimates for the preceding intercensal period are revised. The table below shows how the ERP is calculated.
Source: Australian Demographic Statistics - 2001 Census edition (Cat. no. 3101.0)
(a) Preliminary estimates. Estimates will be finalised in the September Quarter 2002 issue of Australian Demographic Statistics due to be published in March 2003.
*Under-enumeration: Although every effort is made by census collectors to locate every dwelling and household within their allocated area, sometimes this is not possible and generally this can lead to an undercount. An undercount is possible for a number of other reasons. For a more detailed definition, please refer to the 2001 Census Dictionary (Cat. no. 2901.0).
|Components of ERP, 7 August 2001 ('000) (a)|
Census Count,actual location
|Plus Resident absent interstate|
|Less Interstate visitors|
|Less Overseas visitors|
Census count, place of usual residence
|Plus Allowance for under-enumeration*|
|Plus Residents temporarily overseas|
ERP on 7 August 2001 (census night)