Microdata and TableBuilder: Australian Census Longitudinal Dataset

A complete list of data items included on the ACLD file is provided in an Excel spreadsheet that can be accessed from the Data downloads section.

All data items are created at the person level. This includes data items relating to the family and household of the person selected in the sample. For ease of use, these data items have been divided into Person, Dwelling, Household, Family, Spouse Related, and Male and Female parent related groupings.

Users intending to subscribe to the TableBuilder product or use the microdata product in the DataLab should first refer to the Data Items List to ensure the data they require, and the level of detail required, are available and applicable for the intended use.

For information about the quality of the data items in the ACLD please see the Quality Declaration.

Note: While the 2011 and 2016 Censuses were predominantly the same, there were some minor differences. 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 2011 industry data and should not be used to measure longitudinal transitions. 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).

Overseas visitors were excluded from the 2006 ACLD sample. The ACLD, however, does include visitors from within Australia. These are people who were enumerated away from their usual residence on Census Night. Family information cannot be derived for these persons and as such, all family, spouse, and male and female parent related data items are not applicable for visitors.

All dwelling related data items, however, have been made applicable to visitors. This information relates to their dwelling of enumeration on Census Night, not usual residence.

Most household data items are not applicable to visitors, however for four data items, visitors have been included in order to align to standard Census derivations of that data item. These comprise: 

• Total Household Income as stated (weekly) of household in which person was enumerated
• Total Household Income (weekly) of household in which person was enumerated
• Household Income Derivation Indicator of household in which person was enumerated
• Household Composition of household in which person was enumerated.

Any applicable household information for a visitor relates to their place of enumeration, not usual residence.

Where a data item is also applicable to visitors, the usual address indicator data item for the relevant Census year can be used to restrict the table to usual residents only.

The cell comments available in the data item list provide precise information on who is, and is not, applicable for each data item.

The Census household form provides the opportunity to list up to three persons who were temporarily absent from the dwelling on Census Night. A limited amount of information is collected for these persons and it is used to better derive the family and household characteristics of the dwelling. In deriving family and household related data items for the ACLD, information on persons temporarily absent was included where relevant and available. Details are provided in cell comments in the data items list.

Most data items in the ACLD include a 'not applicable' category. The definition of the 'not applicable' category, where relevant, can be found in the section of the relevant year's Census Dictionary (cat. no. 2901.0), including the previous year releases found in the "Past & Future Releases" list.

'Not stated' categories occur when no response has been provided for a data item. All Census data items contain 'not stated' categories except for age, sex, marital status and usual address, as this information is imputed for these items.

Other Census products commonly use the symbol '&' to denote a code value of 'not stated'. In the ACLD, the symbol 'X' or '97' has been used. The codes are listed in the data items list.

The ACLD contains a number of data items that relate to the quality of linkage over the period 2006 to 2011, and 2011 to 2016 and have been collectively named Quality Indicators. The first of these are consistency flags. These variables measure the consistency of reporting on linked records between the time points. The following consistency flags can be found in the Quality Indicators folder of the TableBuilder data item tree and in the ACLD microdata product available in the DataLab:

• Age
• Sex
• Birthplace of Person
• Birthplace of Female Parent
• Birthplace of Male Parent
• Year of Arrival
• Indigenous Status
• Registered Marital Status
• Highest Year of School Completed
• Hours worked
• Level of Highest Non-School Qualification
• Country of Birth of Spouse or Partner
• Number of Children Ever Born.

Consistency flags can be used with other variables. For example, age inconsistency can be cross tabulated with sex to examine potential gender differences in the reporting of age.

In addition to the consistency flags, "Record linked in 2011” and “Record linked in 2016” flags are also available. These flags can be cross tabulated with other data items to examine linkage rates (that is, the proportion of records linked). For example, cross tabulating the record linked flag with State/Territory of usual residence enables an examination of differences in linkage rates between the states and territories.

The 2006-11-16 TableBuilder file has one weight to benchmark the linked records to the estimated Australian population that was in scope of the 2006, 2011 and 2016 Censuses.

The 2006-11-16 DataLab file has two weights:

• a 2006-11 weight to benchmark the linked records to the estimated Australian population that was in scope of the 2006 and 2011 Censuses
• a 2006-11-16 weight to benchmark the linked records to the estimated Australian population that was in scope of the 2006, 2011 and 2016 Censuses.

The 2006-11-16 ACLD datasets in both TableBuilder and DataLab are single-level files that count persons.

In TableBuilder, data items have first been separated by year of collection. For each year, data items are further divided into the following groups:

• Person - person-level characteristics, covering demographic, culture and language, education, employment and unpaid work topics.
• Family - derived from the characteristics of the family to which the person belongs on Census Night - e.g., age of youngest child in family.
• Household - derived from the characteristics of the household to which the person belongs on Census Night - e.g., total weekly household income.
• Dwelling - derived from the characteristics of the dwelling in which the person was enumerated - e.g., type of dwelling.
• Female Parent - derived from information about the person's female parent, provided the parent was counted in the same family on Census Night - e.g., labour force status of female parent.
• Male Parent - derived from information about the person's male parent, provided the parent was counted in the same family on Census Night - e.g., labour force status of male parent.
• Spouse or Partner - derived from information about the person's spouse/partner, provided the spouse/partner was counted in the same family on Census Night - e.g., highest educational attainment of spouse/partner.
• Geographical Area - geographic classifications on both a usual residence and place of enumeration basis.

There is also a group of items named Quality Indicators, which are consistency flags, imputation flags and movement indicators to assist with the assessment of the suitability of records for inclusion in analysis.

The 2006-11-16 ACLD file contains all sample records from the 2006 Panel, both those that were linked to a corresponding 2011 and 2016 Census record and those that were not. Records that were linked have information for 2006 and 2011, and most have information for 2016. Records that were not linked have information for 2006 only.

Data items for 2006, 2011 and 2016 have a category labelled: "Unlinked record".

• the unlinked record category for 2006 data items is empty. It may take on a value in the future once the file is further augmented.
• the unlinked record category for 2011 data items indicates records from the 2006 Panel sample that were not linked to a corresponding 2011 Census record. These records were not linked to a corresponding 2016 Census record either, i.e., these records have valid information for 2006 but no information for 2011 or 2016.
• The unlinked record category for 2016 data items indicates records from the 2006 Panel sample that were either:

1. not linked to a 2011 Census record and therefore not linked to a 2016 Census record, or
2. linked to a 2011 Census record, but not linked to a corresponding 2016 Census record

Excluding Unlinked Records in TableBuilder

When using the weighted summation option in TableBuilder, no results will be returned for unlinked records, as weights were not applied to these records. Results including unlinked records will only be returned if analysis is performed on unweighted data.

To exclude unlinked records from your analysis, deselect the "Unlinked record" category in each data item before adding it to the table. Such a table would produce a sample count corresponding to the equivalent table run with weights. Refer to the TableBuilder User Guide (cat. no. 1406.0.55.005) for more information on how to select data items for tables.

If the 'unlinked record' category is present on a data item that has already been added to a table, it can be removed by selecting this category within the relevant data item and then pressing the 'Remove from Table' button.

Note that removing any category, such as the 'Unlinked record' category, from a table where data has already been generated will clear all data, meaning the table will need to be rerun.

A complete list of data items included on the ACLD file is provided in an Excel spreadsheet that can be accessed from the Data downloads section.

All data items are created at the person level. This includes data items relating to the family and household of the person selected in the sample. For ease of use, these data items have been divided into Person, Dwelling, Household, Family, Spouse Related, and Male and Female parent related groupings.

Users intending to subscribe to the TableBuilder product or use the microdata product in the DataLab should first refer to the Data Items List to ensure the data they require, and the level of detail required, are available and applicable for the intended use.

For information about the quality of the data items in the ACLD please see the Quality Declaration.

Note: While the 2011 and 2016 Censuses were predominantly the same, there were some minor differences. 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 2011 industry data and should not be used to measure longitudinal transitions. 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).

The new data items on the 2011-16 ACLD released in March 2019 are as follows:

Overseas visitors were excluded from the 2011 ACLD sample. The ACLD, however, does include visitors from within Australia. These are people who were enumerated away from their usual residence on Census Night. Family information cannot be derived for these persons and as such, all family, spouse, and male and female parent related data items are not applicable for visitors.

All dwelling related data items, however, have been made applicable to visitors. This information relates to their dwelling of enumeration on Census Night, not usual residence.

Most household data items are not applicable to visitors, however for four data items, visitors have been included in order to align to standard Census derivations of that data item. These comprise:

• Total Household Income as stated (weekly) of household in which person was enumerated
• Total Household Income (weekly) of household in which person was enumerated
• Household Income Derivation Indicator of household in which person was enumerated
• Household Composition of household in which person was enumerated.

Any applicable household information for a visitor relates to their place of enumeration, not usual residence.

Where a data item is also applicable to visitors, the usual address indicator data item for the relevant Census year can be used to restrict the table to usual residents only.

The cell comments available in the data item list provide precise information on who is, and is not, applicable for each data item.

The Census household form provides the opportunity to list up to three persons who were temporarily absent from the dwelling on Census Night. A limited amount of information is collected for these persons and it is used to better derive the family and household characteristics of the dwelling. In deriving family and household related data items for the ACLD, information on persons temporarily absent was included where relevant and available. Details are provided in cell comments in the data items list.

Most data items in the ACLD include a 'not applicable' category. The definition of the 'not applicable' category, where relevant, can be found in the section of the relevant year's Census Dictionary (cat. no. 2901.0), including the previous year releases found on the "Past & Future Releases" list.

'Not stated' categories occur when no response has been provided for a data item. All Census data items contain 'not stated' categories except for age, sex, marital status and usual address, as this information is imputed for these items.

Other Census products commonly use the symbol '&' to denote a code value of 'not stated'. In the ACLD, the symbol 'X' or '97' has been used. The codes are listed in the data items list.

The ACLD contains a number of data items that relate to the quality of linkage over the period 2011 to 2016 and have been collectively named Quality Indicators. The first of these are consistency flags. These variables measure the consistency of reporting on linked records between 2011 and 2016. The following consistency flags can be found in the Quality Indicators folder of the TableBuilder data item tree and in the ACLD microdata product available in the DataLab:

• Age
• Birthplace of Person
• Birthplace of Female Parent
• Birthplace of Male Parent
• Country of Birth of Spouse or Partner
• Highest Year of School Completed
• Hours worked
• Indigenous Status
• Level of Highest Non-School Qualification
• Number of Children Ever Born
• Registered Marital Status
• Sex
• Year of Arrival

Consistency flags can be used with other variables. For example, age inconsistency can be cross tabulated with sex to examine potential gender differences in the reporting of age.

In addition to the consistency flags, a "Record linked in 2016 Flag" is also available in the Quality Indicators folder. This flag can be cross tabulated with another data item to examine linkage rates (that is, the proportion of records linked). For example, cross tabulating the record linked flag with State/Territory of usual residence enables an examination of differences in linkage rates between the states and territories.

The 2011-16 ACLD datasets in both TableBuilder and DataLab are single-level files that count persons.

In TableBuilder, data items have first been separated by year of collection. For each year, data items are further divided into the following groups:

• Person - person-level characteristics, covering demographic, culture and language, education, employment and unpaid work topics.
• Family - derived from the characteristics of the family to which the person belongs on Census Night - e.g., age of youngest child in family.
• Household - derived from the characteristics of the household to which the person belongs on Census Night - e.g., total weekly household income.
• Dwelling - derived from the characteristics of the dwelling in which the person was enumerated - e.g., type of dwelling.
• Female Parent - derived from information about the person's female parent, provided the parent was counted in the same family on Census Night - e.g., labour force status of female parent.
• Male Parent - derived from information about the person's male parent, provided the parent was counted in the same family on Census Night - e.g., labour force status of male parent.
• Spouse or Partner - derived from information about the person's spouse/partner, provided the spouse/partner was counted in the same family on Census Night - e.g., highest educational attainment of spouse/partner.
• Geographical Area - geographic classifications on both a usual residence and place of enumeration basis.

There is also a group of items named Quality Indicators which are consistency flags, imputation flags and movement indicators to assist with the assessment of the suitability of records for inclusion in analysis.

The 2011-16 ACLD file contains all sample records from the 2011 Panel, both those that were linked to a corresponding 2016 Census record and those that were not. Records that were linked have information for 2011 and 2016. Records that were not linked have information for 2011 only.

Data items for both 2011 and 2016 have a category labelled: "Unlinked record".

• the unlinked record category for 2011 data items is empty. It may take on a value in the future once the file is further augmented.
• the unlinked record category for 2016 data items indicates records from the 2011 Panel sample that were not linked to a corresponding 2016 Census record, i.e., these records have valid information for 2011 but no information for 2016.

Excluding Unlinked Records in TableBuilder

When using the weighted summation option in TableBuilder, no results will be returned for unlinked records in 2016, as weights were not applied to these records. Results including unlinked 2011 records will only be returned if analysis is performed on unweighted data.

To exclude unlinked records from your analysis, deselect the "Unlinked record" category in each data item before adding it to the table. Such a table would produce a sample count corresponding to the equivalent table run with weights. Refer to the TableBuilder User Guide (cat. no. 1406.0.55.005) for more information on how to select data items for tables.

If the 'unlinked record' category is present on a data item that has already been added to a table, it can be removed by selecting this category within the relevant data item and then pressing the 'Remove from Table' button.

Note that removing any category, such as the 'Unlinked record' category, from a table where data has already been generated will clear all data, meaning the table will need to be rerun.

A complete list of data items included on the ACLD file is provided in an Excel spreadsheet that can be accessed from the Data downloads section. The population applicable to each data item is described in the cell comments in this spreadsheet.

All data items are created at the person level. This includes data items relating to the family and household of the person selected in the sample. For ease of use, these data items have been divided into Person, Dwelling, Household, Family, Spouse Related, and Male and Female parent related groupings.

Users intending to purchase the TableBuilder product should first refer to the Data Items List to ensure the data they require, and the level of detail required, are available and applicable for the intended use.

Overseas visitors were excluded from the 2006 ACLD sample. The ACLD, however, does include visitors from within Australia. These are people who were enumerated away from their usual residence on Census Night. Family information cannot be derived for these persons and as such all family, spouse, and male and female parent related data items are not applicable for visitors.

All dwelling related data items, however, have been made applicable to visitors. This information relates to their dwelling of enumeration on Census Night, not usual residence.

Most household data items are not applicable to visitors, however for four data items, visitors have been included in order to align to standard Census derivations of that data item. These comprise:

• Total Household Income as stated (weekly) of household in which person was enumerated
• Total Household Income (weekly) of household in which person was enumerated
• Household Income Derivation Indicator of household in which person was enumerated
• Household Composition of household in which person was enumerated.

Any applicable household information for a visitor relates to their place of enumeration, not usual residence.

Where a data item is applicable to visitors, the Usual Address Indicator on Census Night data item for the relevant Census year can be used to restrict the table to usual residents only.

The cell comments available in the data item list provide precise information on who is, and is not, applicable for each data item.

The Census household form provides the opportunity to list up to three persons who were temporarily absent from the dwelling on Census Night. A limited amount of information is collected for these persons and it is used to better derive the family and household characteristics of the dwelling. In deriving family and household related data items for the ACLD, information on persons temporarily absent was included where relevant and available. Details are provided in cell comments in the data items list.

Most data items in the ACLD include a 'Not applicable' category. The definition of the 'Not applicable' category, where relevant, is explained in cell comments for each data item in the data item list.

'Not stated' categories occur when no response has been provided for a data item. All Census data items contain not stated categories except for age, sex, marital status and usual address, as this information is imputed for these items.

Other Census products commonly use the symbol '&' to denote a code value of Not Stated. In the ACLD the symbol 'x' or ‘97’ has been used. The codes are listed in the data items list

The ACLD contains a small number of data items that relate to the linkage over the period 2006 to 2011 and have been collectively named longitudinal data items. The first of these are consistency flags. These variables measure the consistency of reporting on linked records between 2006 and 2011. The following consistency flags can be found in the Longitudinal folder of the TableBuilder data item tree and in the ACLD microdata product in the DataLab:

• Age
• Birthplace of Person
• Birthplace of Male Parent
• Birthplace of Female Parent
• Sex
• Year of Arrival
• Number of Children Ever Born
• Registered Marital Status
• Highest Year of School Completed
• Level of Highest Non-School Qualification
• Country of Birth of Spouse or Partner
• Age of Spouse or Partner
• Indigenous Status

Consistency flags can be used with other variables. For example, age inconsistency can be cross tabulated with Sex to examine potential gender differences in the reporting of age.

In addition to the consistency flags, a Record linked from 2006 flag is also available in the Longitudinal folder. This flag can be cross tabulated with another data item to examine linkage rates (that is, the proportion of records linked). For example, cross tabulating the Record linked flag with State/Territory of usual residence enables an examination of differences in linkage rates between the states and territories.

The 2006-11 ACLD product in both TableBuilder and DataLab is a single-level file that counts persons and has data items for 2006 and 2011.

In TableBuilder, data items have first been separated by year of collection. For each year, data items are further divided into the following groups:

• Person - person-level characteristics, covering demographic, culture and language, education, employment and unpaid work topics.
• Female Parent - derived from information about the person's female parent provided the parent was counted in the same family on Census Night., e.g. labour force status of female parent.
• Male Parent - derived from information about the person's male parent provided the parent was counted in the same family on Census Night, e.g. labour force status of male parent.
• Spouse or Partner - derived from information about the person's spouse/partner, provided the spouse/partner was counted in the same family on Census Night, e.g. highest educational attainment of spouse/partner.
• Family Related - derived from the characteristics of the family in which the person lives, provided the person was counted at home on Census Night - e.g age of youngest child in family.
• Household Related - derived from the characteristics of the household in which the person lives, provided the person was counted at home on Census Night - e.g. total weekly household income.
• Dwelling Related - derived from the characteristics of the dwelling in which the person was enumerated - e.g. type of dwelling.
• Geographical Area - geographic classifications on both a usual residence and place of enumeration basis.

The ACLD file in TableBuilder contains all sample records from the 2006 Panel, both those that were linked to a corresponding 2011 Census record and those that were not. Records that were linked have information for 2006 and 2011. Records that were not linked have information for 2006 only.

Data items for both 2006 and 2011 have a category labelled: unlinked record.

• the unlinked record category for 2006 data items is empty. It may take on a value in the future once the file is further augmented.
• the unlinked record category for 2011 data items indicates records from the 2006 Panel sample that were not linked to a corresponding 2011 Census record, i.e., these records have valid information for 2006 but no information for 2011.

Excluding Unlinked Records

When using the weighted summation option in TableBuilder, no results will be returned for unlinked records in 2011 as weights were not applied to these records. Results will be returned if analysis is performed on unweighted data only. If desired, this category can be excluded from tables by ensuring that the 'unlinked record' category is deselected before each data item is added to the table. Such a table would produce a sample count corresponding to the equivalent table run with weights. Refer to the TableBuilder User Guide for more information on how to select data items for tables.

If the 'unlinked record' category is present on a data item that has already been added to a table, it can be removed by selecting this category within the relevant data item and then pressing the 'Remove from Table' button.

Note that removing any category, such as the 'unlinked record' category, from a table where data has already been generated will clear all data, meaning the table will need to be rerun.

18/09/2019 

DataLab file updated: 

• 'Type of Internet connection 2016' was updated to 'Dwelling Internet connection 2016' variable name, and category labels updated.

TableBuilder updated:

• 'Type of Internet connection 2016' was updated to 'Dwelling Internet connection 2016' variable name, and category labels updated.

Data Item Lists updated:

• 'Type of Internet connection 2016' was updated to 'Dwelling Internet connection 2016' variable name, and category labels updated.
• Minor typo and formatting improvements.

20/03/2019 

Information added relating to the 2006-11-16 linkage

20/03/2019 

Formatting changes to combine the two separate publications, Microdata: Australian Census Longitudinal Dataset, 2006-2011 and Microdata: Australian Census Longitudinal Dataset, 2011-2016, into one publication.

24/10/2018

TableBuilder updated:

• 'Equivalised Total Household Income (weekly) of household in which person was enumerated in 2016' corrected and replaced
• 'Age Consistency Flag 2011-2016' corrected and replaced
• 'Indigenous Status Consistency Flag 2011-2016' corrected and replaced
• Continuous data items added

30/08/2018

DataLab file updated:

• 'Age Consistency Flag 2011-2016' corrected and replaced
• 'Indigenous Status Consistency Flag 2011-2016' corrected and replaced

29/05/2018

DataLab file updated:

• 'Equivalised Total Household Income (weekly) of household in which person was enumerated in 2016' corrected and replaced

29/03/2018

Minor formatting improvements to Data Item Lists.

06/03/2018

Minor formatting improvements and fixes to links. No changes to data.

22/03/2016

An ACLD test file has been included, to assist ABS Data Laboratory users.

This test file will allow users to generate and test code prior to commencing a session in the ABS Data Laboratory. For more information, please see the ABS Data Laboratory Test File page.

12/02/2016

The ACLD has been re-released in both TableBuilder and the on-site ABS Data Laboratory with a number of enhancements.

In TableBuilder

• three data items (Visa Type, Location of Visa Application, and Applicant Status) added from the Settlement Database that were made available in the Australian Census Migrants Integrated Dataset (ACMID) TableBuilder file;
• additional Census variables, such as Socio-Economic Indexes for Areas (SEIFA) and dwelling location;
• more finely disaggregated data items, for example, year of arrival in Australia in single years and religious affiliation at the three digit level;
• refinements to the consistency flags; and
• a revised weight (replacing the original weight) to better account for net overseas migration between the 2006 and 2011 Census Nights. Users who have analysed the ACLD prior to 12 February 2016 may notice changes to estimates produced with the revised weight. Estimates of population groups will be different with the total weighted population estimate being 19.5 million compared to 18.6 million on the old weight. Proportions are expected to only show small differences when previous tables are compared.

In the ABS Data Laboratory

• variable names changed to be more intuitive;
• refinements to the consistency flags; and
• a revised weight (replacing the original weight) to better account for net overseas migration between the 2006 and 2011 Census Nights.

03/12/2015

The ACLD file available for use through the on-site ABS Data Laboratory has been updated.

This updated version includes three new data items relating to migrants that have been made available via the Settlement Database from the Department of Social Services.
An update of the ACLD TableBuilder file and the ACLD ABS Data Laboratory file is planned for the near future.

02/07/2015

The ACLD is now available as a unit record file that can be accessed through the on-site ABS Data Laboratory network in ABS offices throughout Australia.

For further information please contact microdata.access@abs.gov.au

This new ACLD Microdata Product features some revisions to the original dataset released in TableBuilder in December 2013:

• categories of several data items have been expanded to match the level of disaggregation available in Census TableBuilder
• additional Census data items (including Socio-Economic Indexes for Areas) have been added
• weights have been revised to take better account of migration between 2006 and 2011

To maintain consistency it is planned to release these updates to the ACLD TableBuilder file in the near future.

Terms and definitions applicable to the ACLD can be located via the Census Dictionary Glossary. Additional information on data items is also available in the associated cell comment within the Data Items list. This is available via the Data downloads section.

For information on the institutional environment of the Australian Bureau of Statistics (ABS), including the legislative obligations of the ABS, financing and governance arrangements, and mechanisms for scrutiny of ABS operations, see ABS Institutional Environment.

In April 2012, the ABS became an accredited Integrating Authority under the Commonwealth data integration interim arrangements. A copy of the accreditation claims made by the ABS, which have been verified by an independent auditor, is available on data.gov.au. The ABS only undertakes data integration for statistical and research purposes and where there is a strong public benefit in doing so.

The Australian Census Longitudinal Dataset (ACLD) is released in TableBuilder and as a microdata product in the DataLab. Microdata files are released in accordance with the conditions specified in the Statistics Determination section of the Census and Statistics Act 1905. This ensures that confidentiality is maintained whilst enabling micro level data to be released. More information on the confidentiality practices associated with TableBuilder can be found in TableBuilder, User Guide (cat. no. 1406.0.55.005) on the Confidentiality page. To protect confidentiality of data within the DataLab, users are supervised at all times and must not bring mobile phones, cameras, USB keys, laptops, palm pilots or similar transmission or storage devices into the secure location. All outputs produced by users in DataLab are manually cleared for release after the session.

Data for the Census of Population and Housing used in this product were collected on 8 August 2006, 9 August 2011 and 9 August 2016. The scope of the Census is all persons enumerated in Australia on Census night. The Census covers all areas in Australia and includes persons living in both private and non-private dwellings but excludes: 

• diplomatic personnel of overseas governments and their families
• Australian residents overseas on Census Night and

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, 2006-2016 (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:

• false link - the record pair does not belong to the same individual
• reporting error - information for the same individual was reported differently in 2011 and in 2016
• processing error - the value of a data item was inaccurately assigned or imputed during processing.

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:

• Collection methodology - The ACLD is derived from Census data that is self-reported by households across Australia on Census night. This will differ from other ABS collections which may rely on different collection methodologies (e.g. trained interviewers, administrative sources). In addition, the way survey questions are phrased and the answer options available for a given question may affect the information provided by respondents.
• Reference period - The reference periods for the ACLD are the Census nights of each year. Other collections may use different reference periods.
• Sampling design - The ACLD uses a 5% sample of Census data as its base population. This will differ from other collections that may collect information from the entire population of Australia (e.g. the Census) or from a sample of dwellings (e.g. Labour Force Survey).
• Sampling and non-sampling error - While every effort is made to minimise error, each collection will have some level of error. Survey collections are subject to some level of sampling error, as they are based on information obtained from a sample of dwellings or businesses. The Census is not subject to this type of error, but is subject to some level of undercount. The ACLD is constructed using a sample of records from the Census, and is therefore subject to a level of sampling error of its own.
• Scope and coverage - The ACLD weights benchmark the linked records to the longitudinal population that was in scope of both or all three Censuses. This will be different to cross-sectional estimates which may be benchmarked to a point-in-time population, such as the Estimated Resident Population.
• Linkage error - The ACLD is subject to linkage error, as records from one Census are linked to corresponding records from the subsequent Census. While every effort is made to minimise false links, they can occur. Linkage error will not be apparent in other collections which are not produced through data integration.

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, 2006-2016 (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 microdata.access@abs.gov.au. Users should also familiarise themselves with information available via the Microdata Entry Page.

Any questions regarding access to microdata can be forwarded to microdata.access@abs.gov.au or phone (02) 6252 7714.