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As new panels and information from subsequent Censuses are added to the ACLD, its value as a resource for longitudinal studies of the Australian population will continue increasing.
This paper describes the background and rationale for the ACLD, the data linkage methodology used for producing the 2006 and 2011 ACLD panels and an assessment of its quality.
The 2011 Panel size was increased slightly to 5.7%, to achieve a linked sample size of no greater than 5% of the population after allowing for missed links and people in the 2011 sample not being in scope of the 2016 Census due to death or overseas migration (note that the linked sample size for the 2006 Panel linked to the 2011 Census was only 4.2%.) The 2011 ACLD Panel was released in 2018, consisting of the 2011 Panel sample of records from the 2011 Census linked to the 2016 Census.
In the March 2019 release, the 2006 Panel has been re-linked to the 2011 Census to take advantage of improved linking methodology since the initial release, and has then been linked to records from the 2016 Census.
Linking the ACLD
Data linkage is typically undertaken using a combination of deterministic and probabilistic methods:
For many individuals the linkage process will have accurately matched their corresponding records between Censuses. In some cases, the link will represent different people who share a number of characteristics in common. Some inaccuracy in the linkage will not generally affect statistical conclusions drawn from the linked data, although care should be taken in the interpretation of results. For more information see Section 2 - Data Linking Methodology.
1.2 MULTI-PANEL SAMPLE DESIGN
Without sample maintenance, the ACLD would decline in its ability to accurately reflect the Australian population over time due to:
Linkage bias in longitudinal datasets is unique to those created via data integration, as traditional longitudinal studies employ strategies to ensure they collect information about the same individual over time. In a linked longitudinal dataset, data integration is necessary due to a lack of a common identifier to identify a person's responses over time. Linkage bias occurs where certain populations are more difficult to link than others (e.g. Aboriginal and Torres Strait Islander people, young males), so links are more likely to not be identified for members of these groups and, if they are found, have a higher chance of being inaccurate. If left untreated, the representation of population groups suffering from linkage bias would worsen as each new Census is linked to the ACLD.
The ACLD sample is maintained through application of the Multi-Panel framework, developed by Chipperfield, Brown & Watson (2017). This framework provides an approach for selecting records in the ACLD to create panels which maintain the longitudinal and cross-sectional representativeness of the dataset over time, while minimising the impact of accumulated linkage bias on longitudinal analysis.
The Multi-Panel approach designs multiple overlapping panels, with each panel representing a single Census population (2006, 2011, 2016, etc.), which is then linked to subsequent Censuses. The sample selection strategy for each panel is designed to maintain a linked sample size of 5%, maximise sample overlap between the panels, and introduce new records to the dataset in each panel to account for new births, migrants and missed links in previous panels. This allows flexibility for users, who can draw on the most appropriate panel for their research question.
The sample overlap between the 2006 and 2011 ACLD Panels is illustrated below:
FIGURE 1 - SAMPLE OVERLAP BETWEEN THE 2006 AND 2011 ACLD PANELS
1.3 ACCESS TO THE ACLD
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2080.5 - Information Paper: Australian Census Longitudinal Dataset, Methodology and Quality Assessment, 2006-2016 Quality Declaration
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 20/03/2019