Presentation on theme: "Household Projections for England Yolanda Ruiz DCLG 16 th July 2012."— Presentation transcript:
Household Projections for England Yolanda Ruiz DCLG 16 th July 2012
Overview What are household projections Key data inputs Methodology Overview (used for 2008-based update) Stage 1 Stage 2 Main outputs & dissemination Next update
What are household projections Household projections show the long-term trend (25 years) in household numbers if previous demographic trends were to continue. They are not forecasts as they do not attempt to predict the impact that future government policies or other factors might have on demographic trends. Household projections are a key part of the evidence base on housing requirements. The latest set of projections (2008-based) was published in November 2010.
Key data inputs National and sub-national ONS population projections, by sex and five-year age bands Marital status projections Institutional population (constant at 2001 levels for under 75’s and share constant for over 75s) Census data LFS data Key data inputs
Methodology overview Methodology used for first time in last update (2008-based). The methodology adopted has a two stage approach: Stage 1 uses population projections and projected household representative rates to project household population by age, gender and relationship status Stage 2 uses data from the 1991 and 2001 Censuses to disaggregate into detailed household types Methodology overview
Methodology overview- STAGE 1 Stage 1: National and sub-national population projections are trend based and take into accounts assumptions on future levels of fertility, mortality and migration based on observed levels over a 5-year period ONS marital status projections are used to give 3 relationship groups: - Couples (married and cohabiting, where they live together) - Previously married: i.e. separated, divorced or widowed - single (never married) Institutional population is subtracted from total resident population projections by 5 year age band, sex and marital status, obtaining private household population The number of household is essentially the private household population multiplied by the appropriate household representative rate.
Methodology overview- STAGE 1 Projecting Household Representative Rates Household representative rate= is the probability of anyone in a particular demographic group being part of a separate household (value between 0 and 1) Household representative rates are projected forward using a combination of two fitted trends: a simple logistics and a dampened logistics trend, with LFS data incorporated into projections for the 2002 to 2009 period. Simple logistics trend- trend fitted to ln (Xt / (1-Xt)) Dampened logistics trend- S-shaped curve is fitted to ln (Xt / (1-Xt)) Local authority totals are constrained to regional totals, and these to England totals.
Stage 2: It disaggregates Stage 1 household projections at LA level to 17 detailed household types. Uses 1991 and 2001 census data at LA level by household type and age group of the head of household to generate draft ‘headship rates’ and ‘non-headship rates’. Headship rates= the number of people who head a particular household type within a particular age group and local authority area. It combines three different definitions of household representative: -oldest male then the oldest female if there is no male (used in previous methodology) Census definition – first named person on the Census form Census definition – eldest economically active person then the oldest inactive person Methodology overview- STAGE 2
One person households Male Female One family and no others Couple: No dependant children Couple: 1 dependant child Couple: 2 dependant children Couple: 3+ dependant children Lone parent: 1 dependant child Lone parent: 2 dependant children Lone parent: 3+ dependant children A couple and one or more other adults No dependant children 1 dependant child 2 dependant children 3+ dependant children Lone parent and one or more other adults 1 dependant child 2 dependant children 3+ dependant children Other households HOUSEHOLD TYPES
Stage 2…continued: The draft headship and non-headship rates are extrapolated forward using a two-point exponential method. Projected draft headship rates are constrained to sum to 1 within each age band and local authority district. Draft household projections are calculated by applying projected headship rates to the household projections by age band, constraining these to number of households by local authority from Stage 1. Constrained draft households go through minimum adults checks and dependent children checks before becoming final and aggregated to GOR and England levels. Methodology overview- STAGE 2
Import ONS population projection s England total population by sex, age, marital status S1 START Import ONS marital status projection s Control GOR to ENG Institutional population, England Control GOR to ENG Control LAD to GOR Prison population adjustment Household population Import Census years HRR Import LFS HRR HRR simple logistic trend projection HRR dampened logistic trend projection Stage one households, GORs Weight HRR simple and dampened trends Stage one households, England Stage one households, Local Authorities LFS HRR adjustmen t Control LAD to GOR Stage one Adjust for household representativ e differences Adjust all pensioner household s Aggregate categories Aggregate age-bands S2 START Import LAD Census household type tables Two point extrapolation of headship rates Small count regional adjustment Draft headship, non- headship rates Constrain to sum to 1 within age- band and LAD Draft household s by type, LAD Aggregate LAD household types to GORs Min dependent children correction Min dependent children check Minimum adult correction Minimum adult check Aggregate GOR household types to England Stage two Constrain to stage one households, LAD
Main outputs & dissemination Main Outputs Main projections for England, the regions and local authority districts. Variant national projections based on variant population projections published by ONS. These allow to assess the sensitivity of the household projections to alternative fertility, mortality and migration assumptions. Back projections. Components of household growth. Dissemination National Statistics Release. Live Tables for England, regions and by district, including number of households and household population by household type and age of household reference person. Also tables by number of dependent children and older people. Detailed unrounded data for further analysis. Methodology report & detailed report by contractors
Next update Next set of projections – 2010-based, taking into account: 2010-based national & sub-national main & variant population projections Labour Force Survey data from 2010 onwards. Use of 2011 Census data : Today 2011 Census population and household estimates become available. In Autumn, there are also planned to be ‘short-run’ (5-year) population projections based on 2011 Census. We are considering how to best incorporate this information into our based update. The next set of long-term sub-national projections would be consistent with the new Census, and these would then be taken into account for the 2012-based update of the DCLG projections in Autumn With the new Census data we will be able to assess the differences between projected 2011 household numbers and the 2011 Census results, providing a good diagnostic of the projection method. It may then lead to a review/ update of the projection method.