National Records of Scotland

Preserving the past, Recording the present, Informing the future

Comparison of the 1998-based, 1996-based and 1994-based household projections

Comparison of the 1998-based, 1996-based and 1994-based household projections

Scottish Government Statistical Bulletin Housing Series: HSG/2000/4

The 1998-based household projections were produced using information on households from the 1981 and 1991 Census of Population data, together with the latest set of population projections. This is a slight change from the 1996-based and 1994-based household projections where 1971 and 1991 Censuses of Population data was used (refer to Annex A.4 for further details).

1. Population projections

As stated previously, population projections produced by the National Records of Scotland (NRS) provide one of the main inputs to the household projections. Changes between the 1996-based and 1998-based population projections have a direct impact on the 1998-based household projections compared to the 1996-based household projections.

The population projections are based on population estimates for the base year, and this base population is then projected forward using assumptions about births, deaths and migration.

Chart 2.

Chart - Comparison between 1994-, 1996- and 1998-based Population Projections - Population aged 16  only

For household projections, the relevant population for the formation of households is the adult population aged 16 and over. As chart 2 shows, although the 1998 estimate was slightly lower than the 1996-based projection for 1998, a higher rate of growth in the adult population is projected by the new, 1998-based, figures. This is largely due to changes in the assumption about migration. For the new projections, migration out of Scotland is projected to continue at a loss of 1,000 persons a year from 2001 onwards; a loss of 3,000 persons a year was assumed in the previous projections.

On this basis, we would expect the 1998-based household projections to project a higher rate of growth than the 1996-based household projections.

2. Categories of household type

The categories of household type used for the 1998-based household projections are the same as those used for the 1996-based household projections.

As for the 1996-based projections, the current set of projections has household type defined in terms of the household composition (numbers of adults and children) and the age group of the head of household.

3. 1996-based household projections compared to 1998 household estimate

The 1996-based household projections correctly estimated, to the nearest thousand, the number of households for the projection year 1998: 2,170,000. Although the 1998-based household projections start with the 1998 household estimate as the baseline, the projected increase in the number of households is greater than was projected by the 1996-based projections. Therefore, the 1998-based projections are higher for each projection year than the 1996-based.

The faster growth in household numbers projected by the 1998-based projections compared to the 1996-based projections occurs for two reasons. Firstly, the faster projected growth in adults of the 1998-based population projections compared to the 1996-based population projections, and secondly the fact that trends between the 1981 and 1991 censuses were used for these projections where as trends between 1971 and 1991 were used for the 1996-based figures. (The increase in the number of households between 1971 and 1981 was relatively small compared to the increase between 1981 and 1991 — refer to annex A.4 for further details).

Chart 3 clearly shows the faster rate of growth in the number of households projected by the 1998-based household projections compared to both the 1996-based and 1994-based. By the year 2010, 47,200 more households are projected than by the 1996-based projections.

Chart 3

Chart - Comparison between 1994-, 1996- and 1998-based household projections