1. Broad description
Anonymised microdata files (licensed files) in Australia are referred to as Confidentialised Unit Record Files (CURFs). Key measures undertaken by the Australian Bureau of Statistics (ABS) to protect the data are: requiring anyone who uses the data, and the organizations that employ them, to sign an undertaking with the ABS; obtaining user commitment to confidentiality principles; and perturbing data or reducing detail on files to make it very difficult for units to be identified. CURFs are most commonly made available to users either on a CD-ROM or through a remote access data laboratory (RADL™). CURFs available on RADL™ contain more detail than those on CD-ROM. In selected cases users may have access to a CURF through an on-site data laboratory.
2. Why is it good practice?
Releasing microdata in this manner constitutes good practice as:
- perturbation of data and masking of records is undertaken to maintain the integrity of the data while protecting the confidentiality of an individual's data; and
- placing restrictions on how the data are used, as set out in a legal undertaking to be signed by each user and their organization, ensures both the user and the organization accept responsibility for keeping the data confidential and secure.
3. Target audience
CURFs are aimed at Australian researchers and analysts within government, academia and other non-government organizations, who seek to undertake more in-depth analysis than is possible using tabular aggregated data.
CURFs are not generally released to overseas applicants. In very selected instances the ABS allows overseas researchers to access CURFs via the RADL™ if they are sponsored by a suitable Australian organization. The sponsoring organization is required to sign an undertaking with the ABS.
4. Detailed description
The ABS has adopted a manner of release for CURFs that protects the data in three ways: confidentialising the unit record file to control the detail available; providing modes of access appropriate to the level of detail available; and requiring users and organizations with access to the data to sign an undertaking that restricts how they use the data.
The unit record files are confidentialised by removing name and address information, by controlling and limiting the amount of detail available, and by perturbing or deleting data where it is likely to enable identification of individuals.
Each CURF release is personally approved by the Australian Statistician, following advice from a Microdata Review Panel consisting of three senior executives. The panel makes a detailed assessment of each CURF to ensure that the disclosure risk is low.
There is protection inherent in the different access modes and in the different levels of data provided in each. The ABS provides three different modes of access for CURFs - CD-ROM, the RADL™ and the ABS Data Laboratory (ABSDL). CURFs available on CD-ROM are labelled Basic CURFs and are restricted to a relatively small number of variables released in broad categories. RADL™ users can also access Expanded CURFs that contain more variables and more detail, with extra protection provided by the automatic logging of RADL activity and subsequent audits of this activity. Specialist CURFs contain the most variables and detail and can only be accessed via on-site ABS Data Laboratories.
Each user must apply to be granted access to a CURF, explaining their intended use of the CURF. Both the User and a Responsible Officer of the employing organization must sign a legal undertaking in which they agree:
- access to information about individuals will be restricted to officers of the organization who have signed an individual undertaking with the ABS;
- users will not attempt to identify individuals;
- users will not match the unit data to other files of unit data;
- ABS officers are allowed access as necessary to audit compliance with these rules;
- CURF usage is limited to the specified and approved individual 'Statistical Purpose'; and
- any sensitive printed data and output will be stored in a secure place.
The organization must monitor its officers that have access to the CURF and ensure that all have signed an individual undertaking with the ABS. Access to CURFs are for statistical purposes within an organization. If an individual changes organizations, they must surrender access and notify the ABS.
The responsible officer is generally the head or deputy head of an organization, department or university. They are required to sign an undertaking about the storage and use of the CURF. Breaches can be addressed by sanctions against both the individual user and the organization as well, including removal of access to all microdata for all individuals in the organization.
5. Supporting legislation
The release of microdata by the ABS is governed by legislation; namely, the Census and Statistics Act 1905. This legislation enables the Australian Statistician to release unit record data, provided this is done "in a manner that is not likely to enable the identification of a particular person or organization to which it relates." Details are provided in Section 5 of Annex 1.1.
(i) Allows for a range of access mechanisms to suit a range of uses.
(ii) Allows for access to more detailed data to be granted to users who are able to work with a greater level of environmental protections.
(iii) Microdata protection is partly provided by a legally enforceable undertaking. This means that some protection (e.g. prevention of matching) can be provided through the undertaking.
(iv) Sanctions can be applied against users and organizations that breach the undertakings, providing additional motivation to ensure data access and use is appropriate.
(i) Researchers still believe the protections applied directly to the microdata are too limiting. They believe too much of the detail is not being released, especially for some of the most identifiable sections of the population (e.g. large households).
(ii) It is more costly to support a range of access mechanisms than a single access mechanism.
The Census and Statistics Act 1905 http://scaletext.law.gov.au/html/pasteact/1/580/top.htm
The Statistics Determination 1983 http://scaletext.law.gov.au/html/pastereg/0/414/top.htm
CURF undertakings & the Responsible Access to ABS CURFs Training Manual is at: www.abs.gov.au/websitedbs/D3110129.NSF/85255e31005a1918852558ac00697645/72d92417a0ba71b5ca256d01002c47a4!OpenDocument#Untitled%20Section_6
30 Aug 2013