IPUMS-International

International Integrated Microdata Access System

The first public use sample from an Australian census is the one per cent household sample file released by the Australian Bureau of Statistics (ABS) for the 1981 Census. Prior to that census, the only surviving machine-readable data are in two less flexible forms: aggregate data for small geographical areas such as census collectors' districts, or matrix tapes that inter-relate a limited set of personal characteristics. Archive tapes of aggregate data exist for the 1966 Census onwards. Matrix tapes exist for the 1976 and later censuses.

It is possible to use matrix tapes to simulate microdata by treating cell counts as weights in the analysis (for an example based on a 1976 tape, see F. L. Jones, "Sources of Gender Inequality in Income: What the Australian Census Says", Social Forces, 62, September 1983: 134-52) (local copy in jpeg (1MB) or pdf (5MB) format). However, the analyst is restricted to the range of variables included on the same tape.

Forty-three such tapes exist for the 1976 Census of Australia covering different target populations, for example, all Australians, household heads, persons aged 15 or older, the labour force, the residents of different States, and so on. They also cover different sub-sets of variables, for example, household characteristics, labour force status, fertility experience, family composition, and the like. To establish whether or not any of these tapes will be suitable for a specific analytic purpose, the researcher needs to trawl through this collection, variable by variable, classification by classification, and population by population. For censuses since 1976, researchers will generally find that the public use sample provides a more flexible option. One advantage of matrix tapes, however, is that they relate to full census counts, not a sample.

The 1981 public use sample was the first, and also the most detailed, ever released for an Australian census. The ABS did not then (although it has done so since) truncate major classifications like age, country of birth, year of arrival in Australia, occupation, and year of first marriage into less informative versions than the full detail recorded on the census unit record file.

Public use sample files have now been released for all subsequent censuses, as have a number of ABS special purpose surveys under an agreement reached between the ABS and Universities Australia. Under this agreement, any researcher at a participating Australian university can obtain access to files included under the agreement.

The Australian Social Science Data Archives (ASSDA) provides on-line access to information about its holdings of machine-readable census microdata at its web site.

With regard to matrix tape data, there are no special access conditions beyond the standard undertaking required of all researchers wishing to use data held by the ASSDA. Through its membership of the International Federation of Data Organisations and the ICSPR at the University of Michigan (USA), the ASSDA provides reciprocal access to a very wide range of social science data. The ASSDA is also the office of the Secretary of the Australian Consortium for Social and Political Research Incorporated (ACSPRI). One of ACSPRI's objectives is to facilitate access to Australian and overseas sources of machine-readable data.

With respect to public use sample data for the 1981 and later censuses, all prospective users should initially consult the ASSDA about the current rules governing access.

Under the 2009-2011 Agreement, staff and students at participating Australian Universities can access all data files covered by the agreement. Until appropriate terms under which Australian data may be included in an international database can be negotiated, overseas researchers will need to explore collaborations with eligible Australian researchers in order to access these files. Although information on census microdata is available on the ASSDA website, the ABS, not the ASSDA, controls access to all CURFs covered by the 2009-2011 agreement. The ABS/Universities Australia agreement, and a list of files covered by the agreement, can be consulted at the ABS web site.