1. Projections of future population levels are undertaken by most industrialised countries and by international organisations such as the European Union and the United Nations. A population projection shows what would happen if particular assumptions about future fertility, mortality and net migration were to occur. However, because population projections are not a precise science, an organisation will often produce a range of projections based on alternative assumptions, usually known as variant projections. Normally, one of these projections will be known as the principal, medium or central variant. Strictly, such a projection is still simply just the outcome of a particular set of assumptions, but it is inevitable that users will treat it as being a forecast of the most likely course of future events. The official UK national population projections, produced by the Government Actuary’s Department (GAD), and the regular revisions of world population projections, available on the 'Economic and social development' section of the United Nations website, and Eurostat (Statistical Office of the European Union) fall into this category. Although inevitably subject to error, these projections provide a vital guide to short and long-term planning in many different fields.
2. This report summarises and presents analysis from the available variant projections for Scotland produced by GAD based on the estimated population in mid-2004, and describes some of the special case scenarios ("what if") which they also produce. The UK national population projection’s work transferred from GAD to the Office for National Statistics (ONS) on 31 January 2006, but the results from the projections discussed in this report are still available on the GAD website.