1. The Cohort-Component Method A New Method for Household Projections by Tenure Jan Freeke Glasgow City Council Projections and Forecasts Workshop Housing Demand Projection A Demographic Approach

2. Tenure Projection Model for Glasgow and the Clyde Valley Area Model was developed for Housing Need and Demand Assessment This presentation will cover: description of the model projection results for 2008 to 2025 role and use of the model

3. Used Before for Structure Plan: All-Tenure Household Projection with Subsequent Tenure Split

4. GCV Tenure Model: Projection Using Cohort Component Method by Tenure

5. Description GCV Tenure Model Data Input Requirements: 1)fertility and mortality rates by tenure based on analysis of numbers of births and deaths in relation to population for the following categories of Data Zones: –mainly owner occupied –mainly social rented –significant private rented presence 2)population inflow rates. Source: 1991 and 2001 Census 3)population outflow rates derived from model validation process 1991-2001: outflow rates which “predict” 2001 population by tenure from a 1991 base 4)household formation rates GROS supplied all tenure headship rates for GCV area. Calibration factors adjust for difference in household formation patterns by tenure

10. For 1991 to 2001 period: estimates of population change by tenure from 1991 and 2001 Census inflow rates from 1991 and 2001 Census outflow rates derived from total change minus inflow (total change after adjustment for births and deaths) For 2001 to 2008 period: used Scottish Household Survey data to estimate population change by tenure. adjusted population inflow and outflow rates in the model to “predict” 2008 population by tenure from a 2001 base. Description GCV Tenure Model

12. ASSUMPTIONS USED: projection results by tenure constrained to all-tenure projection results. projected trends in household formation by tenure reflect overall household formation trends. net annual population flows for each of the tenures in 2001-2008 will continue into the future, but adjusted for a lower level of RTB sales. projected RTB sales, at 1,331 per year in 2008-2025, are considerably below recent levels (5,089 per year in 2001-2008). Projection Results GCV Tenure Model

21. Issues: 1.Will private rented sector expand at the rate of 2001-2008? 2.Lower RTB adjustment assumes that all households no longer changing tenure through RTB will stay in the social rented sector Comment: The projected change in the number of households for the social rented sector reflects two impacts, which work in opposite directions: a)Continued net outflow of population from the sector (-3,953 per year), and b)Smaller households (reduction average household size) Projection Results GCV Tenure Model

22. Use of GCV Tenure Model 1)used in parallel with Housing Affordability study Tribal HCH 2)validates an important finding from Tribal study: reductions in demand for social rented housing over the next 17 years will be considerably less than in past decades 3)projected households by tenure ‘controlled’ to all-tenure household projection Role and Use of the Model

23. Advantages of Cohort Component Method 1)focus on population. Better understanding of factors behind tenure change: natural change population effect net flow population effect household formation effect 2)age/household structure of population by tenure relevant for service planning 3)closer link with affordability analysis than former method used for Structure Plan

24. Disadvantages of Cohort Component Method 1)requires more detailed data Fertility and mortality rates by tenure are approximations Needs a Census for full validation 2)how stable are inflow/outflow rates by age/sex? Inflow/outflow concepts more difficult to interpret 3)issues of consistency: sum projections by tenure = all tenure household projection Role and Use of the Model