Some broad guidelines on the appropriate use of SEIFA:
- The indexes are assigned to areas, not to individuals. They indicate the average socio-economic characteristics of the people, families, and households living in the area.
- As measures of socio-economic conditions, the indexes are best interpreted as ordinal measures. They can be used to rank (order) areas, and are also useful to understand the distribution of socio-economic conditions across different areas. Also, the index scores are on an arbitrary scale. The scores do not represent some quantity of advantage or disadvantage. For example, we cannot infer that an area with an index value of 1000 is twice as advantaged as an area with an index value of 500. For ease of interpretation, it is generally recommended that the index rankings and quantiles (e.g. deciles) are used for analysis, rather than using the index scores. Index scores are still provided in the output, and can still be used by more technically adept users. For more information on the index scores, rankings and deciles, please refer to SEIFA Measures.
- The variables that contribute to each index should be considered when deciding which index to use. For example, if a user is interested in finding areas of disadvantage for allocation of services they will probably want to use the Index of Relative Socio-Economic Disadvantage. On the other hand, if a user wanted to focus on finding areas containing relatively high proportions of people in unskilled jobs or with low levels of educational qualifications, the Index of Education and Occupation should be used. A full list of the variables included in each index is provided in each index page (IRSD, IRSAD, IER and IEO).
- The indexes are primarily designed to compare the relative socio-economic characteristics of areas at a given point in time, not to compare individual areas across time (longitudinal analysis using past releases of SEIFA). There are a number of issues that make longitudinal or time series analysis of SEIFA difficult to interpret, and thus it should not be attempted lightly. If comparisons over time are being made, the use of quantiles (e.g. deciles) is recommended, rather than ranks or scores.
Elaboration on each of these broad guidelines can be found in Chapter 6 of the Technical Paper.
Below are three examples of using SEIFA:
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