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Projected Population of Scotland (2012-based)

4. The base population and assumptions used in the projections

4.1. The base population: The projection is based on the National Records of Scotland's population estimates for mid-2012 which means that the 2012 based projections are the first set of projections to incorporate the 2011 Census results. The population covered includes all persons usually resident in Scotland, whatever their nationality. Members of HM forces and non-UK armed forces stationed in Scotland are included; HM forces stationed outside Scotland are excluded. Students are treated as being resident at their term-time address.

4.2. The assumptions about future patterns in fertility, mortality and migration are based on analysis of past trends. The final decisions on assumptions take into account the views of a range of groups who are consulted including a UK expert advisory panel and key users in Scotland. These consultations discussed the likely impact of, for example, increasing child obesity and the demographic effects of the economic downturn.

4.3. The assumptions for the 2012-based projections have been reviewed to take into account two years of extra information on fertility, mortality and migration. The fertility and mortality rates have been updated to reflect the rebased population estimates for all the countries of the UK except Scotland as the rebased population estimates for 2002 to 2010 are not yet available. Hence the results from the 2011 Census have been analysed and this analysis has highlighted no concerns in taking this approach.

4.4. Fertility: The fertility rates used in the projection are based on assumptions about the average completed family size of successive cohorts of women. It has been assumed that the average completed family size will continue to decline from around 1.80 children per woman for those born in the mid-1960s and now reaching the end of their childbearing lives, before levelling off at 1.75 for those born in the 2000s and later. The number of births is expected to rise initially from its 2012-2013 level of around 56,800 to a peak of around 60,600 in 2022-2023 before falling to around 58,200 by 2037. More details on the fertility assumptions are available in Annex A.

4.5. Mortality: Future improvements in mortality rates are based on the trend observed in the period 1961 to 2011. It is assumed that the reduction in mortality rates will tend towards a common reduction at each age of 1.2 per cent per year by 2037 for most ages and then continue to improve at this constant rate thereafter. Based on these rates, expectations of life at birth are projected to increase from 76.5 in 2013 to 81.9 in 2037 for males; and from 80.4 in 2013 to 85.4 in 2037 for females as shown in Figure 9. More details on the mortality assumptions are available in Annex B.

4.6. In Figure 9, the estimates of Expectation of Life are unrebased for 2002-2010 and are rebased from the 2011 Census for the years 2011 and 2012 .These estimated figures are based on calendar year data. The projected figures from 2013 onwards are based on mid-year data.

4.7. The projected Expectation of life (Eol) figure for 2013 has been controlled to the latest provisional deaths figures for the period in the projection. This explains the small dip in Eol at the start of the projection period (mid-2013 figure).

Figure 9: Expectation of life at birth actual1 and projected2, Scotland, 1984-2037

Figure 9: Expectation of life at birth actual and projected, Scotland, 1984-2037

4.8. Migration: In the first six years of the projection higher net inflows are assumed reflecting recent migration trends as described in Section 3.4. From 2018-19 onwards, it is assumed that there will be a net inflow of 15,500 people per year to the end of the projection period, (i.e. the total number of people entering Scotland as migrants is assumed to be 15,500 greater than the number leaving Scotland). This assumption has been derived from analyses of trends in civilian migration to and from the United Kingdom as well as cross-border migration between the four constituent countries. Since the last round of projections, improvements have been made to the methods used to produce the migration assumptions. More information on the review and the methods used can be found on the ONS website. More details on the migration assumptions can be found in Annex C.

4.9. Projected natural change and assumed net migration are not independent of each other. The projected numbers of future births and deaths are themselves partly dependent on the assumed level of net migration. A note considering the overall impact of assumed net migration on the future population growth for the UK is available at: ONS migration note.

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