The Western Australia Parliamentary Library Socio-Economic Indexes for Areas (SEIFA) measure the relative level of socio-economic disadvantage and/or advantage based on a range of Census characteristics. Two of the SEIFA indexes: the Index of Relative Socio-Economic Disadvantage (IRSD) and the Index of Relative Socio-Economic Advantage and Disadvantage (IRSAD) can be selected below.

Index of Relative Socio-Economic Disadvantage (IRSD)

This index contains only disadvantage indicators (e.g. unemployment, low incomes or education levels, single parent families, low skilled occupations, poor English proficiency), so is best used to distinguish between disadvantaged areas, but doesn’t differentiate between those areas which are highly advantaged, and those just lacking a lot of disadvantage (with population close to the middle). This index is most commonly used for funding allocations and advocacy, because it highlights the areas of most need.

Index of Relative Socio-Economic Advantage and Disadvantage (IRSAD)

This index contains indicators of disadvantage as well as additional indicators of advantage (e.g. professional occupations, high income, higher education levels, high rent, large dwellings), Characteristics are also weighted differently than the IRSD, so areas do score differently on either measure. Often the IRSAD index will show a more "spread out" distribution with a greater range of scores from very high to very low, due to its ability to measure advantage above the average level.

SEIFA indexes are a good place to start to get a general view of the relative level of disadvantage in one area compared to others, but it is important to also look at these underlying characteristics as they can differ markedly between areas with similar SEIFA scores and shed light on the type of disadvantage being experienced.

A higher score on the index means a lower level of disadvantage, or (in the case of IRSAD only) a higher level of advantage. A lower score on the index means a higher level of disadvantage on both indexes, and a lack of advantage on the IRSAD.

The percentile column indicates the approximate position of this small area in a ranked list of Australia’s suburbs and localities in 2021. It's meant to give a broad indication of where the area sits within the whole nation. A higher number indicates a higher socio-economic status. For instance, a percentile of 72 indicates that approximately 72% of Australia’s suburbs have a SEIFA index lower than this area (more disadvantaged), while 28% are higher. This applies a comparison to suburbs even when the index concerned doesn’t relate to a suburb.