Australian Bureau of Statistics
Census Data Quality
There are many issues which can affect the quality of Census data. This page provides access to general information on Census data quality, specific details on issues affecting the quality of different Census characteristics, and access to an up-to-date list of known data errors and corrections.
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 are produced for each Census data item and include the non-response rate for each variable and a brief outline of any known data quality problems. These can be accessed through links at the top of this page. Fact Sheets are also produced comparing non-response rates over the past 2 Censuses.
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. Such information will be added to the 2006 Census Data Quality Statements over time as evaluation work is completed.
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 Census Reference and Information page including Data Quality Statements, Frequently Asked Questions and Product Briefs.
An extensive range of standard products is available from the Census at the Census Data online page. For further details, see the Census Products page.
This page first published 25 October 2007, last updated 3 April 2009