Population
Service age groups
About this topic
Service age groups divide the population into broad life-stage bands such as children, young adults, working-age adults, and older people. The groupings are designed to reflect typical demand for age-based services and facilities rather than exact five-year cohorts.
This view is useful for planning childcare, schools, recreation, aged services, and other community infrastructure. It works best alongside five year age groups, household type, and dwelling data, which add more detail about who is living in an area and how needs may change over time.
Interpretation notes
- This is a derived grouping rather than a direct Census question, so the age bands are planning-oriented summaries built from standard age data.
- Percentages relate to the total population; use five year age groups when exact cohort detail matters.
Related topics
Key insight
In 2021, Tertiary education and independence (18 to 24) was the most common category among residents in Cossack (WA), accounting for 64.3% (9 people). This share was higher than Karratha (C) (7%). Since 2016, the biggest change was in Parents and homebuilders (35 to 49), which decreased by 1,376 people and 18.7 percentage points.
Section overview
Age structure - Service age groups
Cossack (WA) - Total persons (Usual residence)
This table summarises service age groups for Cossack (WA) in 2021 for persons, with comparison against Karratha (C) and change since 2016.
Age structure - Service age groups snapshot
2021 distribution by category for Cossack (WA), with comparison markers for Karratha (C).
Babies and pre-schoolers (0 to 4)
2021 count
0
% of total
0.0%
Change from 2016
-4.6pp
0
0.0%
-4.6pp
Primary schoolers (5 to 11)
2021 count
0
% of total
0.0%
Change from 2016
-8.9pp
0
0.0%
-8.9pp
Secondary schoolers (12 to 17)
2021 count
0
% of total
0.0%
Change from 2016
-8.1pp
0
0.0%
-8.1pp
Tertiary education and independence (18 to 24)
2021 count
9
% of total
64.3%
Change from 2016
+56.9pp
9
64.3%
+56.9pp
Young workforce (25 to 34)
2021 count
6
% of total
42.9%
Change from 2016
+30.0pp
6
42.9%
+30.0pp
Parents and homebuilders (35 to 49)
2021 count
0
% of total
0.0%
Change from 2016
-18.7pp
0
0.0%
-18.7pp
Older workers and pre-retirees (50 to 59)
2021 count
0
% of total
0.0%
Change from 2016
-14.7pp
0
0.0%
-14.7pp
Empty nesters and retirees (60 to 69)
2021 count
0
% of total
0.0%
Change from 2016
-12.5pp
0
0.0%
-12.5pp
Seniors (70 to 84)
2021 count
0
% of total
0.0%
Change from 2016
-9.4pp
0
0.0%
-9.4pp
Elderly aged (85 and over)
2021 count
0
% of total
0.0%
Change from 2016
-2.9pp
0
0.0%
-2.9pp
Chart view
Age structure - Service age groups change
Absolute change in category counts between 2016 and 2021.
Babies and pre-schoolers (0 to 4)
-336
-4.6pp
Primary schoolers (5 to 11)
-653
-8.9pp
Secondary schoolers (12 to 17)
-595
-8.1pp
Tertiary education and independence (18 to 24)
-534
+56.9pp
Young workforce (25 to 34)
-943
+30.0pp
Parents and homebuilders (35 to 49)
-1,376
-18.7pp
Older workers and pre-retirees (50 to 59)
-1,085
-14.7pp
Empty nesters and retirees (60 to 69)
-920
-12.5pp
Seniors (70 to 84)
-694
-9.4pp
Elderly aged (85 and over)
-211
-2.9pp
Data table
Service age groups for Cossack (WA). Age structure - Service age groups. 2021 and 2016 counts, percentages, and change compared with Karratha (C).
| Category | 2021 | 2016 | Change | |||||
|---|---|---|---|---|---|---|---|---|
| Count | % | Karratha (C)% | Count | % | Karratha (C)% | Count | pp | |
| Babies and pre-schoolers (0 to 4) | 0 | 0.0% | 8.5% | 336 | 4.6% | 9.5% | -336 | -4.6pp |
| Primary schoolers (5 to 11) | 0 | 0.0% | 12.5% | 653 | 8.9% | 11.8% | -653 | -8.9pp |
| Secondary schoolers (12 to 17) | 0 | 0.0% | 8.1% | 595 | 8.1% | 6.9% | -595 | -8.1pp |
| Tertiary education and independence (18 to 24) | 9 | 64.3% | 7.0% | 543 | 7.4% | 7.8% | -534 | +56.9pp |
| Young workforce (25 to 34) | 6 | 42.9% | 18.5% | 949 | 12.9% | 21.3% | -943 | +30.0pp |
| Parents and homebuilders (35 to 49) | 0 | 0.0% | 27.4% | 1,376 | 18.7% | 26.3% | -1,376 | -18.7pp |
| Older workers and pre-retirees (50 to 59) | 0 | 0.0% | 11.1% | 1,085 | 14.7% | 11.0% | -1,085 | -14.7pp |
| Empty nesters and retirees (60 to 69) | 0 | 0.0% | 5.3% | 920 | 12.5% | 4.3% | -920 | -12.5pp |
| Seniors (70 to 84) | 0 | 0.0% | 1.5% | 694 | 9.4% | 1.0% | -694 | -9.4pp |
| Elderly aged (85 and over) | 0 | 0.0% | 0.0% | 211 | 2.9% | 0.1% | -211 | -2.9pp |
| Total | 14 | 100.0% | 100.0% | 7,375 | 100.0% | 100.0% | -7,361 | 0.0pp |