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7.1 The Office for National Statistics produces projections for Scotland for up to 100 years ahead. Results for the first 75 years of this period are available from the National Statistics website (http://www.statistics.gov.uk) and results beyond this are available on request. However, projections this far ahead become increasingly unreliable.
7.2 ONS also produces a number of "variant" projections as well as the "principal" projection which most of this report concentrates on. These variant projections are based on alternative assumptions of future fertility, mortality and migration. The variants are produced to give users an indication of the inherent uncertainty of demographic behaviour, especially for the long-term projections. The purpose is to illustrate plausible alternative scenarios and not to represent upper or lower limits for future demographic behaviour. These projections are simply ‘scenarios’ (the certain outcome of a given set of assumptions), rather than forecasts of the most likely course of future events.
7.3 The scenarios in this publication are, in addition to the principal projection, six standard high/low variants associated with the three components of fertility, life expectancy and migration, a special case ‘zero migration’ variant, and the combination variants which produce the high and low population. These final two variants are produced by combining the high (or low) variant assumptions for fertility, life expectancy and migration and can, for all practical purposes, be consider as giving plausible upper and lower bounds for future total population size. Annex D gives more information about these variants, and the remaining variants which will be released in November.
Figure 11 Actual and projected total population Scotland, under the 2008-based principal and selected variant projections, 1983-2083
7.4 Figure 11 and Table 7 show Scotland’s population under each of the alternative variant projections.
7.5 The high fertility variant results in a 2033 population that is 0.16 million higher than the principal projection. This is due to the extra births associated with the higher fertility assumption. In contrast, the low fertility variant results in the population in 2033 being 0.15 million lower than the principal projection.
7.6 The high life expectancy variant projects fewer deaths and a population in 2033 which is 0.06 million higher than the principal projection. The low life expectancy variant, on the other hand, results in a population which is 0.06 million lower in 2033 than the principal projection.
7.7 Table 8 shows the projected components of population change in the period to 2033 in the principal projection, the high and low migration variants and the zero migration variant. This shows the effect of different migration assumptions on the size of the future population. Under each of these projections the fertility and mortality assumptions are the same but the number of births and deaths change. This highlights the fact that the numbers of births and deaths are partly dependent on the assumed level of net migration.
7.8 The principal projection shows Scotland’s population increasing by 0.38 million (7.3 per cent) between 2008 and 2033. By comparison, the zero migration projection indicates a 0.04 million (0.7 per cent) decrease and the high migration variant projects a 0.63 million (12.2 per cent) increase. The total effect of migration in the principal projection is therefore to add 0.41 million people to Scotland’s population by 2033 (0.38 million plus 0.04 million after the effects of rounding) and, under the high migration variant, to add 0.67 million (0.63 million plus 0.04 million). It is clear that the projected increase in Scotland’s population between 2008 and 2033 under the principal projection is dependent on continuing migration into Scotland.
7.9 As Figure 12 shows, under all of the variant projections, and the principal projection, Scotland’s age structure is projected to change dramatically between 2008 and 2033. In each case, the number of people aged 60 and over is projected to increase significantly, (particularly the number aged 75+) while, in most cases, the numbers in each of the age categories below 60 are projected to decrease. This is further demonstrated by Figure 13 which shows that the average age of Scotland’s population increases under all of the available variant projections.
7.10 Figure 14 shows that the dependency ratio (number of dependents per 100 people of working age population) will rise under all available variant projections although the increase in the state pension age to 66 between 2024 and 2026 will result in a short term decrease. Amongst the available variants, the biggest projected increase in the dependency ratio occurs under the natural change only variant (70.3 in 2033) and the lowest occurs under the low fertility variant (65.3 in 2033).
Figure 12 Percentage change in age structure under the 2008-based principal and selected variant projections, 2008-2033
Figure 13 Average age of Scotland’s population under the 2008-based principal and selected variant projections, 2008-2033
Figure 14 Dependency Ratios (dependents per 100 working age population) under the 2008-based principal and selected variant projections, 2008-2033
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