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2006 Census Quality Declaration

Institutional Environment

For information on the institutional environment of the ABS, including the legislative obligations of the ABS, financing and governance arrangements, and mechanisms for scrutiny of ABS operations, please see ABS Institutional Environment.


The Australian Census of Population and Housing is the official count of population and dwellings and collects details of age, sex and other characteristics of the population.

The Census aims to measure the number and key characteristics of people in Australia on Census Night. All people in Australia on Census Night are in scope, except foreign diplomats and their families. Visitors to Australia are counted regardless of how long they have been in the country or how long they plan to stay. Australian residents not in the country on Census Night are out of scope of the Census.

Topics collected by the Census change from time to time. There must be a demonstrated national need for Census data for policy development, planning and program monitoring. Details on the changing content of Censuses from 1911 to 2006 can be found in Appendix 3 of How Australia Takes a Census (cat. no. 2903.0). A copy of the 2006 Census Household Form is included in the Appendix to the 2006 Census Dictionary.

A small number of new questions and classifications were used in the 2006 Census. These questions were on: core activity need for assistance, unpaid work, number of children ever born, and type of internet connection for the dwelling. Revised classifications were used for the coding of occupation, industry, ancestry, language, and religion. For more detail see 2006 Census Dictionary entry What's new for 2006.


The Census and Statistics Act requires the Australian Statistician to conduct a Census on a regular basis. Since 1961, a Census has been held every 5 years. The 2006 Census was the 15th national Census for Australia and was held on 8 August 2006.

For the 2006 Census, first release data was available on the ABS website on 27 June 2007, and second release data on 25 October 2007.


The ABS aims to produce high quality data from the Census. To achieve this, extensive effort is put into Census form design, collection procedures and processing. There are four principle sources of error in Census data which quality management aims to reduce as much as possible; they are respondent error, processing error, partial or non-response and undercount. For more detail, see 2006 Census Dictionary entry Managing Census Quality.

The Census is self-enumerated, and respondents sometimes do not return a Census form or fail to answer every applicable question. Persons are imputed into dwellings for which no form was returned, together with some demographic characteristics for these people. These same demographic characteristics are imputed if not provided by respondents on a returned form. However, the majority of output classifications include a 'Not Stated' category to record the level of non-response for that data item.

Data Quality Statements in the Census Dictionary (cat. no. 2901.0) contain information about any known issues affecting the quality of data published in the 2006 Census, including non-response rates. Fact Sheets (2914.0.55.001) are also produced comparing non-response rates for the 2006 and 2001 Censuses.

Census of Population and Housing - Details of Undercount, Aug 2006 (cat. no. 2940.0) presents estimates of net undercount for the 2006 Census.


It is important for Census data to be comparable and compatible with previous Censuses and also with other data produced by the ABS and wider community. The ABS, and the Census, uses Australian standard classifications where available and appropriate to provide data comparability across statistical collections. These include standards for occupation, and geographic areas, for example. For more details regarding classifications used in the Census see the 2006 Census Dictionary entry About Census Classifications and the relevant entries for each classification.

For previous Censuses, Census Working Papers provide comparison of Census data with other ABS data. For example, the 2001 Census Working Paper 03/09, on the Qualification data, provided a comparison with the 2001 ABS Survey of Education and Work. For the 2006 Census, such information is included in the Data Quality Statements in the Census Dictionary (cat. no. 2901.0) – for example, in the quality statement for Non-School Qualification: Level of Education (QALLP).

Where changes are made to the Collection Districts (the smallest area for which data is released) from one Census to the next, a comparability indicator is assigned which can be used to approximate links between geographic areas over time. The ABS has used this information to prepare a definition of 2001 SLAs which can be used with 2006 Census data. The Time Series Profile utilises this concordance.


The Census provides a wealth of data about the Australian community through a suite of standard products and data customised for individual requirements. The 2006 Census Dictionary is a comprehensive reference guide designed to assist users to determine and specify their data requirements, and to understand the concepts underlying the data. It provides details of classifications used and a glossary of definitions of Census terms.

A number of other resources can be accessed from the 2006 Census Reference and information pages.


An extensive range of standard products is available from the Census at the Census Data & analysis page.

If the Census information you require is not available as a standard product or service, then ABS Consultancy Services can help you with customised services to suit your needs. Contact 1300 135 070 from within Australia or +61 2 9268 4909 from overseas for all your Census and other information needs. Alternatively, please email

Historical data quality

2006 Census

2001 Census

1996 Census

1991 Census

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