1. Household Projections Dorothy Watson General Register Office for Scotland Household Estimates and Projections Branch

2. Four sets of information are used to produce household projections:  Population Projections  Communal Establishment Rates  Headship Rates  Household Estimates

3. Overview of Household Projection Process Population Projections Communal Establishments Private Population Projected Headship Rates Projected Households Household Estimates 1991 and 2001 Head of House Census data

4. Household types and age groups Household projections are produced for each local authority area, broken down into seven household types (based on the number of adults and children living in the household and sixteen age groups.

5. Population Projections There are three components of population change  Mortality  Fertility  Migration These three components together with the base population estimate for the starting year (2008) combine to form a projection of the population from one year to the next. Population projections by age group, by gender and by council area are needed for household projections. Example:

6. Communal Establishments (CEs) CEs include residential schools, student halls, adult and children’s care homes, prisons etc. The Communal Establishment Rate is the proportion of the population of a particular age group and gender who are resident in a CE. The calculated CE rate for each age group and gender is kept constant for the entire projection period.

7. Private Population The private population is calculated by subtracting those who live in CEs from the projected population. Private Population = Projected Population x (1 – CE rate) = 7,572 x (1 – 0.005716) = 7,529

8. Headship Rates The proportions of households by council area, household type and age group of the head of household are known for each of the 1991 and 2001 Census years. Example

9. Projected Headship Rates The headship (and non-headship rates) are projected forward using the modified two-point exponential model. where:

10. Projected Headship Rates Example: The headship rate for 2008 is calculated from the known headship rates for 1991 and 2001. Since 0.27313 < 0.28227 then k = 0 and the equation becomes Headship rates for other years are calculated in a similar way.

11. Projected Headship Rates Age group of head of household = 40 to 44 Household type = 2+ adults, 1+ children Projected headship rates 1991 and 2001 Census headship rates

12. Constrained Headship Rates The projected headship (and non-headship) rates are constrained in two ways  they cannot individually go above1 or below 0  they sum to 1 within an area and age group 0.03382  1.01170 = 0.03343

13. Projected Households The household projections are calculated by applying the constrained projected headship rates to the total private population projections. 15,058 x 0.06903 = 1,040

14. Final Adjustments  The projected numbers of households are controlled so that figures for local authorities sum to the total for Scotland.  The total numbers of households within each local authority are adjusted to equal the latest annual household estimates. To preserve trends, projections are also adjusted by the same proportion.  Finally figures are adjusted to ensure that the minimum number of adults required to fill the projected households is not greater than the projected private adult population and a similar check is carried out for children. The most recent 2008- based household projections for Scotland can be found on the GROS website http://www.gro-scotland.gov.uk/