SEIFA 2021 is a suite of four summary measures produced by the ABS from social and economic information in the 2021 Census of Population and Housing. The indexes reflect the socio-economic wellbeing of a geographic area, rather than that of individuals. They were calculated at the Statistical Area Level 1 (SA1), and reflect SA1 characteristics. For each index, every geographic area in Australia is given a SEIFA score which measures how relatively 'advantaged' or 'disadvantaged' that area is compared with other areas in Australia.

Each index summarises a different aspect of the socio-economic conditions of people living in an area. They each summarise a different set of social and economic information. The indexes provide more general measures of socio-economic status than is given by measuring income or unemployment alone, for example.

The four indexes in SEIFA 2021 are:

• Index of Relative Socio-economic Disadvantage (IRSD): IRSD is a general socio-economic index derived from Census variables related to disadvantage, such as low income, low educational attainment, unemployment, and dwellings without motor vehicles.
• Index of Relative Socio-economic Advantage and Disadvantage (IRSAD): IRSAD is a continuum of advantage (high values) to disadvantage (low values) which is derived from Census variables related to both advantage and disadvantage, like household with low income and people with a tertiary education.
• Index of Economic Resources (IER): IER summarises variables relating to the financial aspects of relative socioeconomic advantage and disadvantage. These include indicators of high and low income, as well as variables that correlate with high or low wealth.
• Index of Education and Occupation (IEO): IEO summarises variables relating to the educational and occupational aspects of relative socio-economic advantage and disadvantage. This index focuses on the skills of the people in an area, both formal qualifications and the skills required to perform different occupations.

The concept of relative socio-economic disadvantage is neither simple, nor well defined. SEIFA uses a broad definition of relative socio-economic disadvantage in terms of people's access to material and social resources, and their ability to participate in society. While SEIFA represents an average of all people living in an area, SEIFA does not represent the individual situation of each person. Larger areas are more likely to have greater diversity of people and households.

The Australian Statistical Geography Standard (ASGS) (ABS Australian Statistical Geography Standard (ASGS)) is the main geographical framework for the 2021 Census.

Data cubes for the SEIFA 2021 indexes are available for the following geographic units:

• Statistical Area Level 1 (SA1);
• Statistical Area Level 2 (SA2);
• Local Government Area (LGA);
• State Suburb (SSC); and
• Postal Area (POA).

The basic geographic unit used to create SEIFA 2021 is SA1. LGAs are larger geographic units in the ASGS. POAs are an SA1-based approximation of Australia Post postcodes.

The data cube for the SA1 level indexes contains the index scores for each of the four indexes, as well as the associated ranks, deciles and percentiles at the national and state/territory level. All other data cubes are derived from the SA1 level data cube.

Population Distribution and SA1 Distribution data cubes have also been released by the ABS to assist users in understand the diversity of the socio-economic conditions of SA1s within larger areas.

SEIFA indexes are assigned to areas, not to individuals. They indicate the collective socio-economic status of the people living in an area. A relatively disadvantaged area is likely to have a high proportion of relatively disadvantaged people. However, such an area is also likely to contain people who are not disadvantaged, as well as people who are relatively advantaged.

The data elements listed below are used to determine the geographic unit which can be examined on the SEIFA indexes.

Statistical Area Level 1 (SA1): For an SA1 geographic unit either of the following data elements can be collected:

• Person—area of usual residence, statistical area level 1 (SA1) code (ASGS Edition 3) N(11); or
• Address—statistical area, level 1 (SA1) code (ASGS Edition 3) N(11)

Statistical Area Level 2 (SA2): For an SA2 geographic unit the following data element can be collected:

• Person—area of usual residence, statistical area level 2 (SA2) code (ASGS Edition 3) N(9).

Collection of locality, postcode and state/territory

The collection of information about a person's or service provider organisation's locality, postcode and state/territory enables the geographical entity to be ascertained which can then be examined in the relevant SEIFA index. The collection of residential postcode + locality + state/territory can be mapped to SA2. Where locality, postcode and state/territory are collected, there are a number of concordance/correspondence files available from [email protected] which can assist in assigning geographic area codes, such as: 

• 2021 Urban centres and localities (and postcode and state/territory) to 2021 SA2

Summary: Census of Population and Housing: Socio-Economic Indexes for Areas (SEIFA), Australia, 2016 (ABS cat no 2033.0.55.001)

Socio-Economic Indexes for Areas (SEIFA) - Technical Paper 2016 (ABS cat no 2033.0.55.001)