3.1 The base population: The projection is based on the Registrar General's population estimates for mid-2006. The population covered includes all persons usually resident in Scotland, whatever their nationality. Members of HM 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.
3.2 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 1.85 children per woman for those born in the early 1960s and now reaching the end of their childbearing lives, before levelling off at 1.65 for those born in the 1990s and later. The number of births is expected to continue the recently observed rise before peaking at around 57,600 in 2011 and falling to around 50,300 in 2031. More details on the fertility assumptions are available in Annex A.
3.3 Mortality: Future improvements in mortality rates are based on the trend observed in the period 1961 to 2005. It is assumed that annual rates of reduction in mortality rates will tend towards a common reduction at each age of 1.0 percent a year by 2031 for most ages and then continue to improve at this constant rate thereafter. However, for those born in the years 1923 to 1940 the assumed rates of improvement in and after 2031 rise from 1.0 percent a year for those born before 1923 to a peak of 2.5 percent a year for those born in 1931 and then decline back to 1.0 percent a year for those born in 1941 or later. In line with the long-term trends, it has been assumed that the mortality rates for Scotland will continue to be higher at most working ages than those for England & Wales. Based on these rates, expectations of life at birth are projected to increase from 74.7 in 2005 to 80.4 in 2031 for males; and from 79.5 in 2005 to 84.8 in 2031 for females as shown in Figure 5. More details on the mortality assumptions are available in Annex B.
Figure 5 Expectation of life at birth, Scotland, 1981-2031
1 2006-based projections
3.4 Migration: It is assumed that from 2012-13 onwards there will be a net inflow of 8,500 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 8,500 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. In the first six years of the projection higher net inflows are assumed, reflecting recent trends as described in Section 2.4. See Annex C for more details on the migration assumptions.