6541.0.30.001 - Microdata: Income and Housing, Australia, 2017-18 Quality Declaration 
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 13/11/2019   
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The 2017–18 Survey of Income and Housing (SIH) Basic CURF contains information at Household, Income Unit, Person and Loan levels. More information can be found at the 'File Structure' section of this publication.

CURFs allow users to interact with survey data to their own, unique specifications. Uses include:

  • Investigating data
  • Producing tabulations
  • Undertaking statistical

While CURFs provide a great deal of flexibility, limitations on analysis can be impacted by factors such as sample size, the data classifications used, and conditions of use for the file.

More information on the additional detail and data items on the Basic CURF can be found at the 'Data Item' section of this publication.


The 2017–18 SIH Basic CURF is released under the Census and Statistics Act 1905. The Act allows for the release of unit record data, provided this information is not likely to identify an individual person or organisation. As a result there are no names or addresses of survey respondents on the Basic CURF. Other steps, including the following list of actions, have been taken to protect the confidentiality of respondents. The 2017–18 SIH Basic CURF contains unit records relating to most survey respondents.

Protective provisions include:
  • On the Basic CURF, households with seven or more persons were reduced to a maximum size of six persons. This reduction also resulted in the deletion of several whole income units, mainly single person records.
  • Most income items, and some wealth and loan data items have been protected using perturbation. During this process, selected item values are adjusted to prevent identification of survey participants while preserving the overall statistical validity of the data.
  • Some variables have had values ranged or collapsed, or had maximum values reduced. The latter is a process called topcoding whereby all variable values that exceed a threshold value are reduced.
  • For records with unusual combinations of characteristics, a household or person level item was changed to decrease the chance of identification. Details that were commonly changed include geography, age, country of birth, industry or occupation.

As a result of these protective measures, population estimates obtained from the Basic CURF are slightly different to the other 2017–18 SIH products. Variation in key items and populations are addressed in the Basic CURF sample reconciliation tabulations document available from the 'downloads' tab. This table provides a guide to the difference between CURF and the unconfidentialised file, using indicators such as mean, percentiles and ratios.

Steps to confidentialise the datasets that are available on the Basic CURF are taken for three main purposes:
  • Maintain the confidentiality of survey respondents
  • Ensure the integrity of the datasets
  • Maximise the value of survey content

Prospective users should first ensure that the SIH CURF product will suit their data needs. Prior to purchase, you can review whether the topics and level of detail you require are available on the 2017–18 SIH Basic CURF. As an alternative measure, data that has been obtained in the SIH but is not contained on the CURF files may be available via DataLab, TableBuilder, or a tailored service request to client.services@abs.gov.au. The ABS Privacy Policy outlines how the ABS handles any personal information that you provide to us.

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