Estimated Resident Population (ERP)
The Estimated Resident Population (ERP) is the official measure of the Australian population, and is based on the concept of usual 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. The ERP includes usual residents who are overseas for less than 12 months and excludes overseas visitors who are in Australia for less then 12 months.
In the Census year, the ERP is first calculated at the Census date (8 August for the 2006 Census), and is then backdated to calculate the ERP at 30 June of the Census year. After each Census, estimates for the preceding intercensal period are revised to ensure that the total intercensal increase agrees with the difference between the estimated resident populations at the two 30 June dates in the respective Census years.
In the compilation of the 30 June ERP for a Census year, three important adjustments are made to the Census count based on Place of usual residence.
The ERP as at 30 June in the Census year is updated quarterly using administrative data relating to births, deaths, overseas migration and interstate migration. At the Statistical Local Area (SLA) level, reliable statistics on migration are not available, therefore the ERP at this level is updated annually using regression models taking into consideration indicators of population change.
- The first is an adjustment for Census underenumeration. The level of underenumeration is derived from the Post Enumeration Survey (PES) which is conducted soon after the Census, and from estimates based on demographic analysis.
- The second adjustment is the inclusion of the estimated number of Australian residents who are temporarily overseas on Census Night and are therefore not covered by the Australian Census. Using data on residents returning in the 12 months after the Census date, an estimate of the number of residents temporarily overseas is made. This estimate is based on data provided by the Department of Immigration and Multicultural Affairs using completed incoming passenger cards for Australian residents returning to Australia.
- The third adjustment occurs because the Census is not conducted on 30 June. For example, the 2006 Census was held on 8 August and population estimates at 8 August were back-dated to 30 June. This was accomplished using data from births and deaths registrations, overseas arrivals and departures data and estimates of interstate migration for the period 1 July to 8 August.
The ERP by age and sex is published annually at national, state and SLA level. The ERP by country of birth is also published annually at a national level, while marital status ERP is calculated every five years (i.e. as at 30 June in the Census year). National and state/territory ERP, by sex, is published quarterly.
More information on the ERP can be found in the ABS publication Australian Demographic Statistics (cat. no. 3101.0), produced quarterly, and Population by Age and Sex, Australian States and Territories (cat. no. 3201.0), produced annually. ERPs for SLAs are published in Regional Population Growth, Australia and New Zealand (cat. no. 3218.0). More information on demographic publications is available at the ABS web site <http://www.abs.gov.au> under Themes/People/Demography.
See also Census counts, Place of enumeration, Place of Usual Residence (PURP).