Population and household growth and property markets

Buyers quote “the suburb grew 8 per cent” without saying which object grew. People, official usual residents, occupied dwellings and empty dwellings move for different reasons. Name the object, then do the arithmetic.

QuickStats SAL20361, Census night 2021: 24,896 people; 11,040 occupied private dwellings; average 2.1 people per household; 5,712 family households, 3,774 lone-person, 1,554 group. 5,712 + 3,774 + 1,554 = 11,040 occupied dwellings. That identity is a Census snapshot. It is not 2026 ERP.

If a later ERP for a matching geography is higher, that is more usual residents on the ERP method. It is not 11,040 plus a made-up household increment. Dividing new ERP by 2.1 (the 2021 average household size) invents households the ABS did not publish. To talk about household change you need two Census household or occupied-dwelling counts on the same geography, or an ABS household estimate that states its method. Between Censuses, write that the household figure is the last Census figure.

If two Censuses on the same geography show 400 more occupied dwellings, and the register shows 650 dwellings completed in those years, supply ran ahead of occupied-dwelling change by about 250. That describes those years. It does not describe the next five. Completions are not always occupied. See housing supply.

These mistakes turn a people count into a dwellings story. Name the series before you quote the number.

• Quoting population growth as housing demand.
• Building an annual household series by dividing ERP by the last Census average household size.
• Reading a planning projection as a count.
• Comparing growth across unmatched boundaries.
• Treating unoccupied dwellings as vacant rentals. Holiday houses and dwellings between occupants sit in that Census count.

It does not establish tenure, income or that growth will continue. Districts cannot say what has happened to household numbers since the last Census. Only population has an official intercensal estimate. Past growth is not future demand. A planning-department household projection is a model with stated assumptions. Read the assumptions. Do not file it next to ERP as if both were counts.

Suburb profiles show Census population with its date when loaded. Household statistics appear only where the source publishes them for that geography. Districts does not publish projections and does not describe suburbs as high-growth.

On the ABS page, read whether the table is Census QuickStats, a Community Profile, ERP, or a household projection. Note the geography code and the date. Do not join two of those into a homemade annual household line. Household and family projections published by the ABS are models that apply living-arrangement propensities to ERP. They are useful as scenarios. They are not a substitute for a second Census count on the suburb you are buying in.