INTERCENSAL DIFFERENCE

Rebasing revises the ERP for the end point of the intercensal period. However, as the components (births, deaths and migration) for the intercensal period do not change with rebasing, there is a difference between the new population change and the sum of the components. This is referred to as the intercensal difference, and reflects the combined sum of errors and variation in the rebased ERP at the start of the intercensal period, the components of growth for the intercensal period, and the rebased ERP at the end of the intercensal period. Intercensal difference can only be measured after each rebasing process once the end point ERP has been calculated.

Intercensal difference is calculated by subtracting the newly rebased 30 June Census year ERP from the unrebased ERP for the same point in time, i.e. as updated from the previous Census updated using the components of population change. It is illustrated in Figure 5 and also explained by the following equation:

Intercensal difference = P_u – P_r

where:
P_u represents the end point unrebased ERP
P_r represents the end point rebased ERP.



For the 2011–2016 intercensal period, the preliminary intercensal difference was 78,700. Final intercensal difference will be calculated when final rebased ERP has been prepared.

	1986	1991	1996	2001	2006	2011	2016 (c)
	PERSONS ('000)
NSW	11.9	2.4	–15.8	–27.0	10.5	45.4	–10.0
Vic.	3.9	7.0	–20.9	35.6	–36.6	24.4	–108.7
Qld	–32.0	11.1	15.9	5.8	–38.1	9.1	–6.9
SA	–9.4	10.4	4.5	–9.6	–13.5	3.4	–4.7
WA	–18.4	29.9	–3.3	11.5	–8.2	-4.4	57.4
Tas.	0.4	–6.3	–1.1	–1.8	–1.0	0.3	1.4
NT	–6.3	–6.7	–5.2	–0.2	–4.0	-1.0	–0.5
ACT	5.5	4.2	–1.2	–4.3	–5.4	0.4	–7.1
Australia (b)	–44.4	51.9	–27.5	10.6	–96.0	77.7	–78.7
	PERCENT OF POPULATION AT 30 JUNE OF END YEAR
NSW	0.22	0.04	–0.25	–0.41	0.15	0.63	–0.13
Vic.	0.09	0.16	–0.46	0.74	–0.71	0.44	–1.76
Qld	–1.22	0.34	0.48	0.16	–0.93	0.20	–0.14
SA	–0.68	0.72	0.31	–0.63	–0.86	0.21	–0.27
WA	–1.26	1.83	–0.19	0.60	–0.40	-0.19	2.24
Tas.	0.09	–1.35	–0.23	–0.39	–0.20	0.05	0.28
NT	–4.08	–4.05	–2.86	–0.11	–1.89	-0.43	–0.22
ACT	2.12	1.45	–0.39	–1.36	–1.62	0.12	–1.75
Australia (b)	–0.28	0.30	–0.15	0.05	–0.46	0.35	–0.33
(a) In this table, negative numbers mean that the unrebased ERP underestimated the rebased ERP and positive means that the unrebased ERP was an overestimate.
(b) Excludes Other Territories.
(c) Preliminary intercensal difference.

For more details on the intercensal difference, refer to the Feature Article: 'Rebasing of Australia Population Estimates Using the 2016 Census' in Australian Demographic Statistics, Dec 2016 (cat. no. 3101.0).