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Population

Volume 483: debated on Tuesday 18 November 2008

To ask the Chancellor of the Duchy of Lancaster what the most recent forecast is from the Office for National Statistics of the proportion of population growth (a) directly attributable and (b) indirectly attributable to migration in each of its projections of population size. (234137)

[holding answer 10 November 2008]: The information requested falls within the responsibility of the UK Statistics Authority. I have asked the authority to reply.

Letter from Karen Dunnell, dated November 2008:

As National Statistician I have been asked to reply to your question asking what the most recent forecast is of the proportion of population growth (a) directly attributable and (b) indirectly attributable to migration in each of its projections of population size (234137).

The most recent national population projections, based on mid-2006 population estimates, were published by the Office for National Statistics on 23 October 2007. The principal projection was produced using the main assumptions of future levels of fertility, mortality and migration. However, to give users of the projections an indication of the effect of higher or lower assumptions, a number of variant population projections were also produced.

An understanding of the overall effect of migration on population growth can be obtained by comparing the results of the principal and high and low migration variant projections with those of the ‘natural change’ (or zero migration) variant projection. Table A below gives projected components of population change for the UK in the period to 2031 in the principal projection, the high and low migration variants and the natural change variant projection.

Table B shows how the projected population growth to 2031 is broken down between the assumed level of net migration and projected natural change. Natural change is then further broken down into that projected in the absence of migration and the additional natural change from the assumed level of net migration. So, taking the principal projection for example, some 47 per cent of population growth is therefore directly attributable to the assumed number of net migrants. The remaining 53 per cent is attributable to projected natural increase (of which 31 per cent would occur in the absence of net migration and 23 per cent arises from the effect of net migration on natural change). In total, therefore, some 69 per cent of population growth in the period to 2031 in the principal projection is attributable, directly or indirectly, to future net migration.

Projected population figures are unchanged since my previous response to PQ 169089 (3 December 2007) concerning the same subject.

Table A: Projected population change, United Kingdom 2006-31

Thousand

High migration variant

Principal projection

Low migration variant

Zero migration variant

Population at mid-2006

60,587

60,587

60,587

60,587

Population change (2006-31)

Births

20,305

19,847

19,390

17,458

Deaths

14,291

14,247

14,202

14,244

Natural change

6,014

5,601

5,188

3,214

Net migration

6,382

4,912

3,442

0

Total change

12,396

10,513

8,630

3,214

Population at mid-2031

72,983

71,100

69,217

63,801

Table B: Projected population growth by component, United Kingdom, 2006-31

High migration variant

Principal projection

Low migration variant

Total population increase between 2006 and 2031 (Thousand)

12,396

10,513

8,630

Resulting from:

Assumed net migration

6,382

4,912

3,442

Natural change assuming no migration

3,214

3,214

3,214

Additional natural change from assumed level of net migration

2,800

2,387

1,974

Percentage of population growth 2006-31 resulting from:

Assumed net migration

51

47

40

Natural change assuming no migration

26

31

37

Additional natural change from assumed level of net migration

23

23

23

Source:

Migration and Population. Growth:

http://www.gad.gov.uk/Demography_Data/Population/2006/methodology/mignote.asp