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The ACLD is built upon a 5% sample of records taken from a particular Census that is then linked to following Censuses. There are currently two samples, 2006 and 2011, with each being representative of the Australian population at the time of the Census collection.
Overseas visitors are excluded from the 2006 and 2011 ACLD Panel samples. Visitors within Australia to private and non-private dwellings on Census Night are included
The Census collects information on demographics, income, labour force, unpaid work, dwelling characteristics and family and household relationships.
For more information, see How Australia Takes a Census, 2006 (cat. no. 2903.0), How Australia Takes a Census, 2011 (cat. no. 2903.0), Census of Population and Housing: Understanding the Census and Census Data, Australia, 2016 (cat. no. 2900.0), and the 2006, 2011 and 2016 issues of the Census Dictionary (cat. no. 2901.0).
The Census of Population and Housing is conducted every five years. For further information see the publications How Australia Takes a Census, 2006 (cat. no. 2903.0), How Australia Takes a Census, 2011 (cat. no. 2903.0) and Census of Population and Housing: Understanding the Census and Census Data, Australia, 2016 (cat. no. 2900.0).
The first wave of Census data for the ACLD was from 2006, the second wave was from 2011, and the third wave was from 2016.
Microdata from the 2006-11 ACLD was first made available in December 2013. The 2011-16 data was available from February 2018, and the 2006-11-16 data available from March 2019.
The ACLD is a random 5% sample of persons enumerated in Australia on either Census Night, 2006 or Census Night, 2011 which has been linked using statistical techniques to records from successive Censuses. False links can occur during the linkage process as even when a record pair matches on all or most linking fields, it may not actually belong to the same individual. The nature of the process used for the ACLD linkage means that while the methodology is designed to ensure links obtained are to a high degree of accuracy, some false links may be present within the ACLD dataset. There is an estimated 5-10% false link rate in the original linkage of the 2006-2011 ACLD, an estimated 5% false link rate in the re-link of the 2006-2011 ACLD and an estimated 1% false link rate in the 2011-2016 linkages.
Sampling error occurs because only a small proportion of the total population is used to produce estimates that represent the whole population. Sampling error refers to the fact that for a given sample size, each sample will produce different results, which will usually not be equal to the population value. There are two common ways of reducing sampling error - increasing sample size and/or utilising an appropriate selection method (for example, multi-stage sampling would be appropriate for household surveys). Given the large sample size for the ACLD (1 in 20 persons), and simple random selection, sampling error is minimal.
The ACLD sample was weighted to an estimate of the population that was resident in Australia on Census Night for the relevant linkage periods. For example, the linkage of the 2011 Panel to the 2016 Census is weighted to an estimate of the population that was resident in Australia at both the 2011 and 2016 Censuses. The weights adjust for missed links and Census undercount.
Information on methodology, linkage quality and weighting can be found in Information Paper: Australian Census Longitudinal Dataset, Methodology and Quality Assessment, ACLD (cat. no. 2080.5). Steps are taken to confidentialise the data made available on TableBuilder in such a way as to maximise the usefulness of the content while maintaining the confidentiality of respondents selected in the ACLD sample. As a result it may not be possible to exactly reconcile all the statistics produced from the microdata with other published statistics. Further information about the steps taken to confidentialise the microdata can be found in TableBuilder, User Guide (cat. no. 1406.0.55.005) on the Confidentiality page.
A small percentage of linked records have inconsistent data, such as a different country of birth at the two time points or an age inconsistency of more than one year. Inconsistencies may be due to:
ACLD microdata contains a large number of data items and in some cases the level of detail has been collapsed from that described in the Census Dictionary. For more information on the level of detail provided, please see the associated Data Items list.
While the 2011 and 2016 Censuses had predominantly the same questions and were processed in a similar way, there were some differences between them.
For example, a number of changes were made to how industry of employment information was collected for the 2016 Census. The ABS advises this data is not directly comparable to the previous Census Industry of employment data, and should not be used to measure longitudinal transitions between industries from 2011 to 2016. For further information refer to Industry of Employment (INDP) in Census of Population and Housing: Understanding the Census and Census Data, Australia, 2016 (cat. no. 2900.0).
Notable data items that are different between Census years are personal, family and household income. Income was collected in ranges and these ranges are different in different Census years. The ACLD does not include an adjustment to income data for inflation.
Some data items were derived differently between Censuses. In these instances, to aid comparability, the 2006 and 2011 variables were re-derived to make them consistent with the 2016 derivation.
For more information on the differences between the 2006, 2011 and 2016 Censuses see What's New for 2011? and What's New for 2016?
Estimates derived from the ACLD may differ to those derived from other sources. This is due to a range of factors including:
For these reasons, while the results from the ACLD are considered to be broadly representative of the Australian population, they are not strictly comparable with statistics derived from other collections.
For detailed information about the different methodologies for each collection, refer to the Explanatory Notes within each release.
For detailed information regarding the differences between the Census and Labour Force collections, refer to The 2016 Census and the Labour Force Survey in Census of Population and Housing: Understanding the Census and Census Data, Australia, 2016 (cat. no. 2900.0).
For detailed information regarding Census data, including changes to Census questions and data quality statements for each Census data item, refer to Understanding the data in Census of Population and Housing: Understanding the Census and Census Data, Australia, 2016 (cat. no. 2900.0).
This publication should be referred to when using the microdata. It contains information on the Methodology, File Structure, Using the ACLD in TableBuilder, The ACLD in the DataLab, Conditions of Use and the Data Items list.
Detailed information on methodology, linkage quality and weighting can be found in Information Paper: Australian Census Longitudinal Dataset, Methodology and Quality Assessment, ACLD (cat. no. 2080.5). The ABS publishes extensive information on Census Data Quality.
The Australian Census Longitudinal Datasets, 2006-11, 2011-16 and 2006-11-16 can be accessed through TableBuilder and the DataLab.
These microdata products are available to approved users. Users wishing to access the microdata should read the How to apply for Microdata web page, before applying for access by emailing firstname.lastname@example.org. Users should also familiarise themselves with information available via the Microdata Entry Page.
Any questions regarding access to microdata can be forwarded to email@example.com or phone (02) 6252 7714.
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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