§ Mr. Cartwrightasked the Secretary of State for the Environment (1) what factors lie behind the differential between the figure of new households in the south-east projected for the decade 1981 to 1991 in his Department's report "1981-Based Estimates of Numbers of Households in England, the Regions, Counties 1981–2001", in February and the projected figure given by officials of his Department to the south-east regional plan inquiry in December 1984;
(2) if he will publish in the Official Report the figures for the postulated rates of household formation in the south-east for the decade 1981 to 1991 which were being projected by his Department in (a) October 1981, (b) November 1984 and (c) February 1985;
(3) what features of the model used by his Department for forecasting rates of household formation in its February report "1981-Based Estimates of Numbers of Households in England, the Regions, Counties 1981–2001", are new; and on what basis the old model has been discarded;
(4) what is the basis of his Department's projection in the report "1981-Based Estimates of Numbers of Households in England, the Regions, Counties 1981–2001", concerning the increase in the category Other Households in the Greater London Council area in the decade 1981 to 1991 and subsequent decrease in the following decade;
(5) what is the basis of his Department's projection in the report "1981-Based Estimates of Numbers of Households in England, the Regions, Counties 437W 1981–2001", concerning the increase in the category Other Households in Hampshire in the decade 1981 to 1991 and subsequent decrease in the following decade.
§ Sir George YoungThe household projections published by the Department are derived from projections of the population of men and women of different ages and marital status by applying the appropriate "headship rates" —the proportions who will head households.
The figures released in 1981 were based on headship rates from the censuses of 1961, 1966 and 1971 extrapolated to 1991. These were applied to "1979-based" population projections published by the Office of Population and Censuses and Surveys, analysed by marital status on the basis of projections on the Government Actuary's Department. Separate headship rates were derived for 24 categories: men, women, ages 15–29, 30–44, 45 but below retirement age, retirement age (men of 65 or over and women of 60 or over); married, widowed or divorced, single.
To incorporate the figures from the 1981 census, a new mathematical procedure was devised to extrapolate from four instead of three sets of data. The projected headship rates were applied to the OPCS "1981-based" population estimates. These incorporated the main census results. Initially the headship rates were derived for and applied to the same age, sex and marital status categories as
South-East Region: Projected Households Thousands 1979-based 1981-based Provisional Published Type of household 1981 1991 Increase 1981 1991 Increase 1981 1991 Increase Married couple 4,003 4,083 80 3,852 3,912 60 3,859 3,920 61 Lone parent 464 514 50 502 597 95 503 641 138 One person 1,616 2,029 413 1,496 1,843 347 1,494 1,900 406 Other 366 381 15 459 500 41 466 581 115 All 6,448 7,006 558 6,309 6,852 543 6,322 7,042 720 Private household population 16,541 16,924 383 16,727 17,132 405 16,727 17,132 405 Average household size 2.57 2.42 2.65 2.50 2.65 2.43 The increase in "other" households in the decade 1981 to 1991 and the decrease in 1991 to 2001 apply generally across the country, not just to London and Hampshire. This reflects a combination of changes in the age structure of the population and of trends in headship rates for households.