2902.0 - Census Update (Newsletter), Sep 1999  
Previous ISSUE Released at 11:30 AM (CANBERRA TIME) 20/10/1999   
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How is the Australian population counted?

To mark Australia's projected population passing 19 million, we would like to take the opportunity to explain the difference between census counts, estimated resident population and population projection.

A census count is a count of every person who spent census night in Australia. 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, 6 August 1996, as opposed to where they normally live. Information for this count is available for all geographic areas from Collection District (CD) level, which average 225 households in size. This type of count provides a snapshot at one point in time, in any given area. Holiday resorts at 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. For this count, characteristics of individuals are coded at the Statistical Local Area level and above. A Statistical Local Area (SLA), as defined in the Australian Standard Geographical Classification, can be a whole or part Local Government Area, or an unincorporated area. SLAs consist of one or more CDs.

The estimated resident population (ERP) is the official estimate of the population and uses the census usual residence count as a basis. It makes certain assumptions on how the population is growing and likely to grow since it was last officially estimated.

To calculate the ERP, census counts are adjusted to exclude overseas visitors, include residents temporarily abroad, and to account for under-enumeration* of the population in the 1996 Census (see table below).

ERP is calculated four times a year, to provide official, and up-to-date estimates of the population.

In addition to being more frequent than census counts, the ERP is adjusted to reflect the true population resident at a particular date. The table below provides an example of the difference between these two concepts.

        Components of Estimated Resident Population, 6 August 1996 ('000)

        census count, actual location
        less overseas visitors
        equals census count, place of usual residence
        plus adjustment for under-enumeration
        plus residents temporarily overseas
        equals ERP on 6 August 1996 (census night)

      • 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 can lead to an undercount. An undercount is possible for a number of other reasons. For a more detailed definition, please refer to the 1996 Census Dictionary (ABS Cat. no. 2901.0).

Population projections are produced by the ABS twice between each census. They are based on the latest ERP and use a combination of assumptions about future levels of births, deaths and overseas migration. The projected populations reflect possible scenarios resulting from the particular combinations of assumptions used.

The ABS population clock uses the latest available ERP and the assumptions published in Population Projections (ABS Cat no. 3222.0) which most accurately reflect prevailing trends. Up to the end of September 1999, the latest ERP is the December 1998 figure, and the assumed components of growth used were:
    • Births - an average number of births per woman of 1.7
    • Deaths - life expectancy at birth of 76.3 years for males and 81.8 years for females
    • Net overseas migration - 90,000 per year.

From these assumptions the population is projected to grow by an average of 558 people per day - from 681 births, 369 deaths, and a net intake of 246 migrants.

Click here to view the population clock.