USING THE SURVEY

LEVELS AND ITEMS

Units used in Survey of Income and Housing (SIH) published output

Analysis of income data is usually carried out using household income measures. As explained in the 'Income' section of this publication, it is usually most appropriate to examine household income when considering economic wellbeing because of the sharing that occurs between members of households. The 'Income' section of this publication also explains that income comparisons are improved if the household income measure is adjusted to reflect the size and composition of the household.

However, when analysing the income distribution, it is the number of people who belong to households with particular characteristics, rather than the number of households with those characteristics, that is of primary interest. This leads to the preference for the equal representation of those persons in such analysis. For example, if the person is used as the unit of analysis rather than the household, then the representation in the income distribution of each person in a household comprising four persons is the same as that for each person in a household comprising two persons. In contrast, if the household were to be used as the unit of analysis, each person in the four person household would only have half the representation of each person in the two person household.

Therefore, the income distribution measures from the SIH are calculated with respect to persons, including children. Such measures are sometimes known as person weighted estimates because the unit of analysis is the person, even though all the characteristics being described are characteristics of the household to which the person belongs. The method of calculation is described in the 'Summary indicators of Income Distribution' section of this publication.

Whereas, estimates of net worth are published using the household as the basic unit of analysis. The data item list, available from the 'downloads' tab of this publication, will show which data items are available for each unit type supported by the SIH.

Households

A household consists of one or more persons, at least one of whom is at least 15 years of age, usually resident in the same private dwelling. The persons in a household may or may not be related. They must live wholly within one dwelling. A group of people who make common provision for food and other essentials of living but live in two separate dwellings are in two separate households.

Most of the published output from the SIH uses the household as the unit of analysis and relates to household characteristics.

Income units

An income unit is one person, or a group of related persons within a household, whose command over income is assumed to be shared. Income sharing is assumed to take place within married (registered or de facto) couples, and between parents and dependent children. The income unit is similar, but not identical, to the unit used in determining the eligibility of people for many government pensions and allowances such as Centrelink payments. Income data and selected income unit characteristics are available on an income unit basis from the SIH, although they are not included in any published tables from the surveys.

Persons

Data at the person level are available for each person aged 15 years and over usually resident in the households included in the SIH. Data relating to characteristics of children aged under the age of 15 years are only available at the household level.

Loans

A household may have one or more loans, and data are available for the characteristics of each loan. These characteristics include the main purpose of the loan, its security, the amount borrowed, and the principal outstanding and weekly repayment, although they are not included in detail in any published tables from the surveys.


REFERENCE PERSON

In some analyses, it is useful to describe a household or income unit using characteristics that are attributes of persons. For example, the analyst may wish to classify households into 'older households' and 'younger households'. One approach used is to designate one member of the household or income unit as the reference person and assume that the characteristics of that person are descriptive of the household or income unit more generally. The reference person is chosen through a set of operating procedures designed to identify the person most likely to be representative of the household or income unit. Households or income units can then be classified according to the age of the reference person, occupation of the reference person, country of birth of the reference person, etc.

Household reference person

The reference person for each household is chosen by applying a selection criteria, to all household members aged 15 years and over. The selection criteria below is applied in the order listed, until a single appropriate reference person is identified:

• the person with the highest tenure when ranked as follows: owner without a mortgage, owner with a mortgage, renter, other tenure
• one of the partners in a registered or de facto marriage, with dependent children
• one of the partners in a registered or de facto marriage, without dependent children
• a lone parent with dependent children
• the person with the highest income
• the eldest person.

For example, in a household containing a lone parent (owner with a mortgage) with a non-dependent child, the one with the higher tenure - i.e. the lone parent - will become the reference person. However, if both individuals have the same tenure (e.g. a couple, owners with a mortgage), the one with the highest income will become the reference person.

Income unit reference person

The reference person for an income unit is the male partner in a couple income unit, the parent in a lone-parent income unit and the person in a one-person income unit.


CONFIDENTIALITY

The Census and Statistics Act, 1905 provides the authority for the ABS to collect statistical information, and requires that statistical output shall not be published or disseminated in a manner that is likely to enable the identification of a particular person or organisation. This requirement means that the ABS must take care and make assurances that any statistical information about individual respondents cannot be derived from published data.

Some techniques used to guard against identification or disclosures of confidential information in statistical tables are suppression of sensitive cells, random adjustments to cells with very small values, and aggregation of data.

To protect the confidentiality of individuals, a technique called perturbation is used to randomly adjust cell values in the SIH published outputs. Perturbation involves small random adjustment of the statistics and is considered the most satisfactory technique for avoiding the release of identifiable statistics while maximising the range of information that can be released. These adjustments have a negligible impact on the underlying pattern of the statistics.

After perturbation, a given published cell value will generally be consistent across all tables. However, adding up cell values to derive a total will not necessarily give the same result as published totals.

The introduction of perturbation in publications ensures that these statistics are consistent with statistics released via services such as Table Builder. To protect confidentiality within SIH publications, some cell values may have been suppressed and are not available for publication but included in totals where applicable.

Future customised data requests from the 2017–18 SIH will also utilise the same technique


DATA ITEM LIST

For details of the data items available from the 2017–18 SIH see the Excel data cube from the 'downloads' tab of this publication.


PUBLICATIONS

User Guide

This publication describes the definitions, concepts, methodology and estimation procedures used in the 2017–18 SIH. Additional material available as part of this publication includes the questionnaires, interviewer prompt cards and a list of SIH output data items and classifications available from the 'downloads' tab.

Income and Wealth

'Household Income and Wealth, Australia, 2017–18' presents key information about household income and wealth from the 2017–18 SIH. It incorporates information previously presented as fact sheets in Household Income and Income Distribution, Australia, 2011–12. It includes estimates of household income and wealth, classified by various characteristics of the households and their residents such as income quintile, main source of household income, family composition, tenure type, age and employment status. It also includes summary child care usage and cost information and superannuation information.

Housing Occupancy and Costs

'Housing Occupancy and Costs' presents data from the 2017–18 SIH on Australian housing occupancy and costs, and it relates these to characteristics of occupants and dwellings such as tenure, family composition of household, dwelling structure, age, income and main source of income. It also includes the value of dwelling estimates and information on recent home buyers.

Imputed Rent

The methodologies for imputed rent estimates used for 2017–18 are explained in 'Estimates of Imputed Rent, Australia, 2015–16'. The availability of imputed rent estimates allows the analysis of household income to be extended to include the imputed rental incomes that flow to people living in homes owned by the occupant and those paying subsidised rent. Such imputations allow for more meaningful comparison of the income circumstances of people living in different tenure types, and to understand changes over time in income levels and the distribution of income when tenures may also be changing over time.


DATA CUBES

All the Excel data cubes from the 2017–18 SIH will be available from the 'Downloads' tab of the publications listed above.

If the information you require is not available from the publication or the data cubes, please contact the National Information and Referral Service (NIRS) on 1300 135 070, (international callers +61 2 9268 4909) or via email <client.services@abs.gov.au>. The NIRS can be contacted from anywhere in Australia between 8:30am and 5:00pm (AEST) Monday to Friday.


SUPPORTING MATERIAL

Supporting material is available to assist data users in analysing the data from the survey. A representation of the computer assisted interview questionnaire, and prompt cards used in the SIH is available on the ABS website. These are available from the 'Downloads' tab of this publication.


MICRODATA ACCESS

For clients wanting to produce their own tabulations and conduct manipulations of survey estimates, microdata is accessible through a variety of products. To protect the confidentiality of individual persons and households some data items are removed from the file and the level of detail for some items is reduced. Microdata access includes:

• TableBuilder - an online tool for creating tables from ABS survey data, where variables can be selected for cross-tabulation.
• Detailed file available via the DataLab - approved users can access a remote desktop environment for in-depth analysis using a range of statistical software packages
• Basic confidentialised unit record file (CURF) - allows approved users interactive access in the user’s own computing environment

Microdata products will be released in July 2019, including DataLab and TableBuilder. The Basic CURF for the SIH will be accessible via the publication 'Microdata: Income and Housing, Australia' from August 2019.

For more information see the Microdata Entry Page on the ABS website.


SPECIAL DATA SERVICES

The published data are only a small portion of the data collected in the surveys. The ABS offers specialised consultancy services to assist data users with more complex statistical information needs. Users may wish to have the unit record data analysed according to their own needs, or require tailored tables incorporating data items and populations as requested by them. A wide range of data items are available - the detailed list of these are available from the 'Downloads' tab of this publication.

Tables and other analytic outputs can be made available electronically or in printed form. However, as the level of detail or disaggregation increases with detailed requests, the number of contributors to data cells decreases. This may result in some requested information not being able to be released due to confidentiality or sampling variability constraints.

All specialist consultancy services attract a service charge and clients will be provided with a quote before information is supplied. If you have any questions or require any more information, please contact the NIRS on 1300 135 070, (international callers +61 2 9268 4909) or via email <client.services@abs.gov.au>.