National Records of Scotland

Preserving the past, Recording the present, Informing the future

Long-term and Variant Projections

Long-term and Variant Projections

1. To address the increasing interest in longer term issues such as pensions and health care the Government Actuary's Department (GAD) has, for the first time, made available longer-term projections for Scotland to 2074. However, projections this far ahead become increasingly unreliable because assumptions are being made, in some cases, about the behaviour of people who have not yet been born. Hence, GAD as well as producing a 'principal' population projection, also produce a number of 'variant' projections, based on alternative assumptions of future fertility, mortality and migration. 

2. The variants are produced because of the inherent uncertainty of demographic behaviour, to give users an indication of this uncertainty, especially for the long-term projections to 2074. 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. At the date this report was written GAD had made available only the six high/low variants and the variant on 'zero migration'. Additional variants will be published on GAD’s website in November 2005. Annex D gives more information about these variants and the assumptions used.

3. Under these alternative, but still plausible, fertility, mortality and migration assumptions, the population at 2031 differs from the principal projection by around up to ± 0.3 million. The uncertainity widens with time - by 2044 it has increased to ± 0.4 million, with further increases to ± 0.8 million by 2074 highlighting the unreliability of projections this far ahead.

4. However, Figure 10 and Figure 11 illustrate clearly that, despite increasing uncertainty the further one goes into the future about the size of the population, the average age of Scotland’s population increases under any plausible assumptions. In addition, Figure 12, shows that the dependency ratio for the number of dependents to 100 people of working age will rise significantly under the principal and also all the variant projections after the change in womens state pension age is complete in 2020.

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