SEIFA MEASURES
The SEIFA indexes are available in spreadsheets on the Downloads tab. Each area has a score, rank, decile, and percentile. Rankings within state or territory are also provided. This section explains each of these measures below.
Scores: A score for a Statistical Area Level 1 (SA1) is created by adding together the weighted characteristics of that SA1. The scores for all SA1s are then standardised to a distribution where the average equals 1000 and the standard deviation is 100. For areas larger than SA1, the scores are a population weighted average of the SA1 scores that correspond to the larger area.
A lower score indicates that an area is relatively disadvantaged compared to an area with a higher score. It is important to remember that the scores are an ordinal measure (discussed in more detail in the "How to Use SEIFA" section), so care should be taken when comparing scores. For example, an area with a score of 1000 is not twice as advantaged as an area with a score of 500.
Ranks: all areas are ordered from the lowest to highest score, then the area with the lowest score is given a rank of 1, the area with the second lowest score is given a rank of 2 and so on, up to the area with the highest score which is given the highest rank.
Deciles: all areas are ordered from lowest to highest score, then the lowest 10% of areas are given a decile number of 1, the next lowest 10% of areas are given a decile number 2 and so on, up to the highest 10% of areas which are given a decile number of 10. This means that areas are divided up into ten equal sized groups, depending on their score.
Percentiles: all areas are ordered from lowest to highest score, then the lowest 1% of areas are given a percentile number of 1, the next lowest 1% are given a percentile number 2 and so on, up to the highest 1% of areas which are given a percentile number of 100. This means that areas are divided up into one hundred equal sized groups, depending on their score.
Ranking within state or territory (rank, decile and percentile): all areas within each state or territory are ordered from lowest to highest score, then ranks, deciles and percentiles are assigned to each area within that state or territory. These state/territory ranks, deciles and percentiles can only be used to compare areas within a single state or territory.