8.1. The Office for National Statistics (ONS) produces projections for Scotland for up to 100 years ahead. Projection results for the next 100 years are available from the ONS website. The reliability of projections decreases as you go further into the future. Therefore projections far into the future should be treated with caution.
8.2. This report concentrates on the principal projection but ONS also produces a number of variant projections. 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.
8.3. The scenarios in this publication, in addition to the principal projection, are six standard high/low variants associated with the three components of fertility, life expectancy and migration, a special case zero migration variant (with natural change only), 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 considered 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 December.
8.4. Figure 15 and Table 7 show Scotland's population under each of the alternative variant projections.
Figure 15: Actual and projected total population of Scotland, under the 2012-based principal and selected variant projections, 1982-2087
8.5. The high fertility variant results in a 2037 population that is 0.17 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 2037 being 0.13 million lower than the principal projection.
8.6. The high and low life expectancy variants project the population to be 0.08 million higher or lower than the principal projection respectively, due to the changes in the number of projected deaths.
8.7. In Figure 15 it can be seen that the single component variants which lead to the highest and lowest projected population for 2037 are the migration variants. Table 8 focuses on the migration variants, and shows the projected components of population change in the period to 2037 for 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. For the high migration variant the increase in the population over the 25 year period due to natural change is 0.13 million whereas with the principal projection natural change only results in an increase of 0.09 million.
8.8. The principal projection shows Scotland's population increasing by 0.47 million (9 per cent) between 2012 and 2037. By comparison, the zero migration projection variant indicates a 0.04 million (1 per cent) decrease and the high migration variant projects a 0.7 million (13 per cent) increase. The total effect of migration in the principal projection summed over the first 25 years is to add 0.38 million people to Scotland's population by 2037 and, under the high migration variant, to add 0.54 million - and this does not take into consideration the increase in natural change as the result of increased migration. It is clear that the projected increase in Scotland's population between 2012 and 2037 under the principal projection is dependent on continuing migration into Scotland.
8.9. As Figure 15 shows, under all of the variant projections, and the principal projection, Scotland's age structure is projected to change dramatically between 2012 and 2037. In each case, the number of people aged 60 and over is projected to increase significantly (particularly the number of persons aged 75+) while, in most cases, the numbers in each of the age categories below 60 are projected to decrease except for children aged 0-15 which are projected to increase under the principal and 4 other variants by 2037. The ageing of the population is further demonstrated by Figure 17 which shows that the average (median) age of Scotland's population increases steadily across the projection period under all of the available variant projections.
Figure 16: Percentage change in age structure under the 2012-based principal and selected variant projections, 2012-2037
Figure 17: Average (median) age of Scotland's population under the 2012-based principal and selected variant projections, 2012-2037
8.10. Figure 18 shows that the dependency ratio (number of dependents per 100 people of working age population) will decrease under all available variant projections until 2020 when it will begin to rise due to the increase in the state pension age to 66 for both men and women. The dependency ratio is then projected to increase year on year until 2034-2035, when the pension age will rise to 67. Amongst the available variants, the biggest projected increase in the dependency ratio from 2012 to 2037 will occur under the natural change only, the high population variant and the high fertility variant. In all three scenarios the dependency ratio is projected to increase from 59 to 69 per 100 working population over the next 25 year period. The smallest increase over the period occurs under the low fertility variant as it only increases to 62 per working age population by 2037.
Figure 18: Dependency ratios1 (dependents per 100 working age population) under the 2012-based principal and selected variant projections, 2012-2037
8.11. Figure 19 shows the ratio of the number of children per 100 working population under each variant projection. The high fertility and high population variant projection show the largest increase over the 25 year period reaching 31 per 100 working age while the low fertility variant shows the largest decrease to 25 per 100 working age.
Figure 19: Children per 100 working age population under the 2012-based principal and selected variant projections, 2012-2037
8.12. Figure 20 shows the ratio of the number of people of state pension age per 100 working population under each variant projection. In the principle and every variant projection there is an increase projected in the number of people of state pension age per 100 working age population. The Natural change variant shows the largest increase over the 25 year period reaching 43 people of state pension age per 100 working age by 2037 while the high migration and low life expectancy variant shows the largest decrease to 37 per 100 working age by 2037.
8.13. As mentioned in previous sections of this report these dependency ratios should be interpreted with caution.
Figure 20: Pensioners per 100 working age population under the 2012-based principal and selected variant projections, 2012-2037
