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Household Projections for Scotland 2006-based

7. Definitions, uses and limitations of the household projections

7.1 Definitions used in the household projections

The following definitions are used in this publication:

Figures in the tables are rounded to the nearest ten. Therefore, the totals shown may not be equal to the sum of the constituent parts.

7.2 Uses

The main use of the household projections is in contributing to the assessment of future housing need and demand. Local authorities make widespread use of the household projections in assessing future housing need and demand, and as a context for planning decisions. The use of household projections for housing and planning purposes is guided by central government policy and guidance (Scottish Planning Policy 3: Planning for Housing (SPP 3) and Housing Need and Demand Assessment Guidance). Projections are only one element to be taken into account in assessing future housing need and demand.

More information about the planning system in Scotland is available from the Scottish Government website at

7.3 Limitations

These household projections have limitations. A projection is a calculation showing what happens if particular assumptions are made. The household projections are trend-based, and are not, therefore, policy-based forecasts of what the Government expects to happen. They do not take into account social and economic factors that may influence the formation of households including policies adopted by both central and local government as well as any imbalances between housing supply and demand. Local planning policies are often intended to modify past trends and development plans may demonstrate departures from the projections that seem better able to fit particular local circumstances.

7.4 Population projections

The household projections are based on the population projections and, as a result, assumptions used for the population projections, such as future migration, fertility and mortality, will have an effect on the household projections. Since smaller areas tend to be affected more by migration, which is hard to predict, projections for these areas tend to be less reliable than those for areas with large populations, and the further into the future the projections are taken, the less reliable they are likely to be.

7.5 The use of Census-based trends in household formation patterns

The household projections use information on household type and age group from the 1991 and 2001 Censuses, projected forward to the end of the projection period. The headship rate is defined as the proportion of people in each age group and household type who are the ‘head’ of a household.

For these projections, changes in household formation patterns between 1991 and 2001 – the most recent 10 year period - are projected forward to 2031. This method assumes that past trends in household formation will continue, but this may not necessarily be the case. The overall number of households is updated every year, but no information is incorporated on changes in household types between Censuses.

With the assistance of the Household Analysis Review Group, the General Register Office for Scotland is investigating ways to refine the household projections methodology.

7.6 Relationship to other projections

These projections apply a single methodology across all local authority areas. Individual authorities may have a wider range of local information – based for example on local population or household surveys – on which to compile local projections. The supporting material on the GROS website should assist in providing an understanding of the basis of our projections. We are happy to provide additional supporting or background material which users would find useful in assessing and using the projections, where possible.

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