Income
Individual Income Quartiles
Individual income quartiles group people aged 15 years and over into four evenly sized income ranges so the distribution of personal income can be compared objectively across areas and over time. The quartile method focuses on relative position in the income distribution rather than raw dollar brackets.
About this topic
Individual income quartiles group people aged 15 years and over into four evenly sized income ranges so the distribution of personal income can be compared objectively across areas and over time. The quartile method focuses on relative position in the income distribution rather than raw dollar brackets.
This topic is useful because direct income amounts are affected by inflation and wider economic change. Quartiles provide a clearer way to compare whether an area is becoming relatively lower, middle, or higher income over time.
Interpretation notes
- This is a derived distribution of personal income for people aged 15 years and over, with each quartile representing a quarter of the income distribution.
- Quartiles show relative position rather than fixed dollar brackets, which makes them more robust for comparisons over time.
Key insight
In 2021, the lowest income quartile held the largest share among residents aged 15 and over in Two Rocks, accounting for 29.2%.
Section overview
Individual income quartiles
Two Rocks - Persons aged 15+ (Usual residence)
This table summarises individual income quartiles for Two Rocks in 2021 for persons, with comparison against Wanneroo (C) and change since 2016.
Chart view
Individual income quartiles snapshot
2021 distribution by category for Two Rocks, with comparison markers for Wanneroo (C).
Lowest group
Medium lowest
Medium highest
Highest group
Individual income quartiles change
Absolute change in category counts between 2016 and 2021.
Lowest group
+228
+2.8pp
Medium lowest
+104
-2.0pp
Medium highest
+100
-1.2pp
Highest group
+153
+0.4pp
Data table
Individual Income Quartiles for Two Rocks. Individual income quartiles. 2021 and 2016 counts, percentages, and change compared with Wanneroo (C).
| Category | 2021 | 2016 | Change | |||||
|---|---|---|---|---|---|---|---|---|
| Count | % | Wanneroo (C)% | Count | % | Wanneroo (C)% | Count | pp | |
| Lowest group | 778 | 29.2% | 25.7% | 550 | 26.4% | 25.5% | +228 | +2.8pp |
| Medium lowest | 668 | 25.1% | 23.7% | 564 | 27.1% | 21.3% | +104 | -2.0pp |
| Medium highest | 566 | 21.2% | 25.6% | 466 | 22.4% | 24.7% | +100 | -1.2pp |
| Highest group | 654 | 24.5% | 25.0% | 501 | 24.1% | 28.5% | +153 | +0.4pp |
| Total persons aged 15+ | 2,666 | 100.0% | 100.0% | 2,081 | 100.0% | 100.0% | +585 | 0.0pp |