National Records of Scotland

Preserving the past, Recording the present, Informing the future

The Base Population and Assumptions Used in the Projection

The Base Population and Assumptions Used in the Projection

The base population:

The projection is based on the Registrar General's population estimates for mid 2003. 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.


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 just under 2 children per woman for those born in the mid to late 1950s and now reaching the end of their childbearing lives, before levelling off at 1.60 for those born in 1975 and later. A downward trend in the number of births is expected, to a projected level of about 45,000 by 2028.


The mortality rates for the projections are based on long-term trends. Generally, mortality rates are projected to fall, initially at varying rates but tending to a reduction of 1.0 per cent a year at all ages by 2027. In line with the long-term trends, it has been assumed that the mortality rates for Scotland will continue to be higher at most ages than those for England & Wales. Based on these rates, expectations of life at birth are projected to increase from 74.0 in 2003-04 to 78.5 in 2027-28 for males; and from 79.1 in 2003-04 to 83.3 in 2027-28 for females.


It is assumed that from 2006 onwards there will be a net outflow of 1,500 per year to the end of the projection period, i.e. the total migration outflow is assumed to be greater than the total inflow. 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 three years of the projection a net inflow is assumed, reflecting recent trends.

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