Population disaggregation

Overview

Scope: The estimated resident population (ERP) of females, aged 50–74, by Indigenous status, at 30 June 2021, based on ABS final estimates. This aligns with the age group of women actively targeted for 2-‍yearly screening by BreastScreen Australia.

ERP numbers were disaggregated (spread out) across the ABS Population Grid (2021) and Mesh Block areas (Australian Statistical Geography Standard Edition 3) using probabilistic methods, partly based on 2021 Census counts (person-level).

With this level of disaggregation, drive times and population estimates could be calculated for small areas (one square kilometre resolution), and results could be produced for any geographic level based on Mesh Blocks.

Details

Notes:

  • Where relevant, geographic boundaries refer to the Australian Statistical Geography Standard (ASGS) Edition 3.
  • Where sparse data were used (Census counts), smoothing techniques were applied to avoid placing reliance on small numbers.

Data inputs – Final population data matched:

  • [P1] Females, aged 50–74, by SA2, 30 June 2021 (preliminary)(a).

Data inputs – Population data used during intermediate steps:

  • [P2] First Nations females, aged 50–74, by state and territory, 30 June 2021 (final)(b)
  • [P3] First Nations females, aged 50–64 and 65+, by IREG, 30 June 2021 (final)(c)
  • [P4] First Nations persons, by SA2, 30 June 2021 (final)(d)
  • [P5] Persons, by Statistical Area Level 1 (SA1), 30 June 2021 (preliminary)(e)
  • [P6] Persons, by Australian Population Grid, 30 June 2021(f)
  • [P7] Persons, by SA2, 30 June 2021 (preliminary)(a).

Data inputs – Other data used to steer disaggregation:

  • [C1] Males and females (Census counts), aged 0–49, 50–64, 65–74 and 75+, by Indigenous status, by SA2 and IREG, 2021(g)
  • [C2] Females (Census counts), aged 50–74, by Indigenous status, by SA2, 2021(h)
  • [C3] Females (Census counts), aged 50–74, by Indigenous status, by SA1, 2021(i)
  • [C4] Females (Census counts), aged 50–74, by SA1, 2021(i)
  • [C5] Persons (Census counts), by SA1, 2021(i)
  • [C6] Persons (Census counts), by Mesh Block, 2021(j)
  • [A1] Address counts (Geocoded National Address File, G-NAF), by Australian Population Grid and Mesh Block, May 2022(k).

Data sources:

  1. ABS (2021) ‘Population estimates by age and sex, by SA2 (ASGS2021), 2001 to 2021' [data set], Regional population by age and sex, accessed 27 October 2022.
  2. ABS (30 June 2021) ‘Table 1: Estimated resident Aboriginal and Torres Strait Islander, non‑‍Indigenous and total populations, States and territories – 30 June 2021' [data set], Estimates of Aboriginal and Torres Strait Islander Australians, accessed 31 August 2023.
  3. ABS (30 June 2021) ‘Table 2: Estimated resident Aboriginal and Torres Strait Islander, non‑‍Indigenous and total populations, Indigenous Regions – 30 June 2021’ [data set], Estimates of Aboriginal and Torres Strait Islander Australians, accessed 31 August 2023.
  4. ABS (30 June 2021) ‘Table 4: Estimated resident Aboriginal and Torres Strait Islander, non‑‍Indigenous and total populations, Statistical Areas Level 2 – 30 June 2021' [data set], Estimates of Aboriginal and Torres Strait Islander Australians, accessed 31 August 2023.
  5. ABS (2023) ‘Estimated Resident Population by Statistical Area Level 1 – 30 June 2011 to 2022’ [customised report], Queensland Government Statistician’s Office, accessed 31 March 2023.
  6. ABS (2021) ‘Australian population grid in ESRI Grid format, 2016 to 2021' [Population grid files], Regional population, accessed 7 September 2022.
  7. ABS (2021) Sex (SEXP) by Age group (AGE5P) and Indigenous status (INGP) and Indigenous Region (IREG) and Statistical Area Level 2 (SA2) [TableBuilder], accessed 4 September 2023.
  8. ABS (2021) Sex (SEXP) by Age group (AGE5P) and Indigenous status (INGP) and Statistical Area Level 2 (SA2) [TableBuilder], accessed 2 April 2023.
  9. ABS (2021) Sex (SEXP) by Age group (AGE5P) and Indigenous status (INGP) and Statistical Area Level 1 (SA1) [TableBuilder], accessed 31 August 2023.
  10. ABS (2021) ‘2021 Census Mesh Block counts' [data set], Census mesh block counts, accessed 29 July 2022.
  11. Geoscape Australia (May 2022) Geocoded National Address File (G-NAF) [data set], accessed [via Data.gov.au] 19 May 2022.

Procedure summary:

Below, square brackets are used to indicate inputs and curly brackets are used to indicate results.

  • [A1] used to split [P6] by Population Grid and Mesh Block → {R1} Persons, by Population Grid and Mesh Block
  • [C6] used to adjust [R1] → {R2} Persons, by Population Grid and Mesh Block
  • [P5] used to benchmark [R2] → {R3} Persons, by Population Grid and Mesh Block
  • [P6] used to benchmark [R3] → {R4} Persons, by Population Grid and Mesh Block
  • [C4]÷[C5] and [P1]÷[P7] used to estimate target population size in [R4] → {R5} Females, aged 50–74, by Population Grid and Mesh Block
  • [P1] used to benchmark [R5] → {R6} Females, aged 50–74, by Population Grid and Mesh Block
  • [C2] used to estimate target population size in [R6] by Indigenous status → {R7} Females, aged 50–74, by Indigenous status, by Population Grid and Mesh Block
  • [C3] used to adjust [R7] → {R8} Females, aged 50–74, by Indigenous status, by Population Grid and Mesh Block
  • [C1] used to disaggregate [P2], [P3] and [P4] → {R9} Males and females, aged 0–49, 50–64, 65–74 and 75+, by Indigenous status, by SA2 and IREG, 2021
  • [R9] used to adjust [R8] → {R10} Females, aged 50–74, by Indigenous status, by Population Grid and Mesh Block.

Limitations

  • The smallest geographic level for which ERPs are officially prepared and validated by the ABS is SA2. In this report, population estimates that are low, cover small areas, are more geographically isolated, or specific to First Nations and non‑‍Indigenous women are subject to greater relative error. For example, estimates of the number of First Nations women or non‑‍Indigenous women in small remote communities should be treated as indicative only.
  • Population disaggregation via proxy data (in this case: Census counts, total populations and G-NAF addresses) is an imperfect process. Proxy data may not be accurate or representative of the target population’s distribution.
  • Population data from 2021 were used, instead of more recent data for 2022, mainly for coherency with Aboriginal and Torres Strait Islander ERPs from 2021, which were the best available at the time of analysis. Where preliminary ERPs have been used, there may be discrepancies with other revised or final ABS estimates.
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