Technical Aspects of the DCLG 2003-based Household Projections

Dave KingAnglia Ruskin University

Outline

2003-based resultsBob Garland later

Data inputsDifferentiation of household membershipModelling trajectoriesEvolution of modellingSub-national modelling issues

2003-based results

Summary Projection Results (E&W)

2003-20265.2 million (ph) population increase 5.1 million household increasereduction of avg hh size 2.3 to 2.1

(millions) 1981 2003 20261981-2003

2003-2026

Households 18.4 22.1 27.2 3.8 5.1Private household population 48.8 51.9 57.1 3.1 5.2Average household size 2.7 2.3 2.1 -0.3 -0.2

Household Composition Characterised by:

decline in married couplesgrowth in cohabiting householdsgrowth in one person households

1981 2003 2026 1981-2003 2003-2026

Household types:

married couple 11.7 10.2 9.4 -1.5 -0.8

cohabiting couple 0.5 2.0 3.5 1.5 1.6

lone parent 0.7 1.7 2.0 1.0 0.3

other multi-person 1.4 1.5 1.9 0.1 0.4

one person 4.2 6.8 10.4 2.6 3.6All households 18.4 22.1 27.2 3.8 5.1

How reasonable at 2026?Modelling: HRR trends look plausible? One person households (38%):

40% Sweden 1990; 35% Germany 1998Average household size (2.1)

2.1 Sweden 1990; 2.2 Germany 1998

1981 2003 2026

% One Person Households 23% 31% 38%

Average household size 2.7 2.3 2.1

Reasons for Increase:Past and Projected

Households (millions) resulting from:

1981-2003

2003-2026

growth in adult population 1.6 2.8ageing of population 0.9 1.1change in marital status -0.5 -0.2household membership rates 1.0 1.0remainder 0.7 0.3

All 3.8 5.1

Data Inputs

Data inputsEstimates to construct the time-series:

Population (age/gender)Marital StatusInstitutional PopulationHousehold membership

To control the national projection:Population projection (age/gender)Marital Status projection

Data quality issuesAvailability:

Census & LFS used; GHS/SEH previously investigated difficult to access and rework historic data to add to categories, change definitions etc

Census, LFS & 03-basedFemales aged 40-44: Composite Household Representative Rates

England and Wales

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1981 1986 1991 1996 2001 2006 2011 2016 2021

HOPS

Census

LFS

Data quality issuesAvailability:

Census & LFS used; GHS/SEH previously investigated difficult to access and rework historic data to add to categories, change definitions etc

Sample size e.g. LFS. Future improvements anticipated.

Census, LFS & 03-basedSNC Females aged 40-44: Composite Household Representative Rates

England and Wales

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1981 1986 1991 1996 2001 2006 2011 2016 2021

HOPS

Census

LFS

Data quality issues

Availability: Census & LFS used; GHS/SEH previously investigated difficult to access and rework historic data to add to categories, change definitions etc

Sample size e.g. LFS. Future improvements anticipated.Treatment of non-response bias re: household composition, particularly OPHConsistency of definitions through the time series (and access to historic data to review and revise)

Consistency of Time-Series?Divorced female non-cohabiting one person household HRRs Eng&Wales

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

1971 1981 1991 2001 2011 2021

55-59 03-based 60-64 03-based 65-69 03-based 70-74 03-based 75-79 03-based 80-84 03-based 55-59 96-based 60-64 96-based 65-69 96-based 70-74 96-based 75-79 96-based 80-84 96-based

Differentiation of household membership:in different categories of population

(beyond age-gender)

Marital Status

Marital Status Married non-cohabitingDivorced non-cohabitingWidowed non-cohabitingSingle non-cohabitingMarried cohabitingDivorced cohabitingWidowed cohabitingSingle cohabiting

Single non-cohabiting having previously cohabited?

Household MembershipFor each age/gender/marital status group:

Household representatives: Concealed family representatives: married couple married couple cohabiting couple cohabiting couple lone parent lone parent other multi-person one-person Non-representatives: wives in married couples cohabiting women other non-representatives

Reasons for Increase 2003-26 :One Person Households

Related to change in: H’hold membership rates (25%)Marital status (22%)

Components of change (households: millions) Nos %adult population 0.9 24age structure 0.7 20marital status 0.8 22household membership rates 0.9 25remainder 0.3 8

All 3.6 100

OPH Household Membership Effect

Among Non-cohabiting:WidowedDivorcedSingle

Wid (M&F) (non-cohabiting) OPH Household Rep Rate 1981-2026

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84 85

+

198120032026

Div Male (non-cohabiting) OPH Household Rep Rate 1981-2026

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84 85

+

198120032026

Single (M&F) (non-cohabiting) OPH Household Rep Rate 1981-2026

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84 85

+

198120032026

Disaggregate OMPH?

“Lone parent” with non-dependent childSame gender cohabiting coupleOther

Disaggregate OPH?

Parent of dependent childParent of non-dependent childFormer couple memberNever-parent or -couple member

Differentiating Transient Populations?

StudentsArmed servicesInternational migrants

Reviewing Concealment?

Currently: concealed familiesReturners to the parental home?Key workers in the parental home?Patient under care?

Differentiating with/without children; dependant/non-dependant?

CouplesHousehold with “absent” child?

At boarding school/universityLiving with other parent but staying over

Modelling Trajectories

Typical Output TrajectoriesFig 12 SFNC 35-39 03-based

00.10.20.30.40.50.60.70.80.9

1

1971

1974

1977

1980

1983

1986

1989

1992

1995

1998

2001

2004

2007

2010

2013

2016

2019

2022

2025

Lone parentOne personOther multiConc. lone parentOther non-rep

Examples of HRR trajectoriesFSNC OPH HRR 03-based

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1971 1981 1991 2001 2011 2021

15-1920-2425-2930-3435-3940-4445-4950-5455-5960-6465-6970-7475-7980-8485+

Cohort effectsSFNC HRR cohort e ffects 2003-based

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1971e 1981e 1991e 2001e 2011p 2021p

15-19 at 2021

25-29 at 2021

35-39 at 2021

45-49 at 2021

55-59 at 2021

65-69 at 2021

75-79 at 2021

“Life-Cycle” method

t-10 t0 t10 t20 15-19

25-29

35-39

45-49

55-59

65-69 75-79

85+

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

96-based SFNC HRRs

0.9-1

0.8-0.9

0.7-0.8

0.6-0.7

0.5-0.6

0.4-0.5

0.3-0.4

0.2-0.3

0.1-0.2

0-0.1

Modified Life-Cycle Method

19711981

19912001

20112021

15-19

20-24

25-290

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Modified Life-Cycle Method

1971 19811991 2001

20112021

15-19

20-24

25-29 30-34

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Modified Life-Cycle Method

1971 1981 1991 20012011

2021 15-19

20-24

25-29 30-34

35-39

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Modified Life-Cycle Method

1971 1981 1991 2001 2011 2021 15-19

25-29

35-39

45-49

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Modified Life-Cycle Method

1971 1981 1991 2001 2011 2021 15-19

25-29

35-39

45-49

55-59

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Modified Life-Cycle Method

1971 1981 1991 2001 2011 2021 15-19

25-29

35-39

45-49

55-59 65-69

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Modified Life-Cycle Method

1971 1981 1991 2001 2011 2021 15-19

25-29

35-39

45-49

55-59 65-69

75-79

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Modified Life-Cycle Method

1971

1981

1991

2001

2011

2021

15-19

30-34

45-49

60-64

75-79

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Evolution of Modelling?

Differentiated Modelling

Currently: one-size-fits all modelling (life-cycle model)Scope for different modelling approaches for differentiated population groups or household membership categories

e.g. lone parents

“Causal” Modelling

full dynamic modelling: key transition rates problematicPartial linking?

e.g. “lone parent with non-dependant” to “lone parent with dependant” over time?or “having previously cohabited” to “cohabiting” over time?

Extend beyond household composition?

Into dwelling consumption: tenure or dwelling size?

Estimating Propensities E&W 2001: Example of Owner Occupier Married Couples

Author’s own estimates

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

15-24 25-34 35-44 45-54 55-64 65-74 75+

age of "head"

8 +over76541 to 3

Sub-national modelling issues top-down process

Restricts sub-national what-ifs?Reconstruct hierarchy?

Integration of population and household projection?

Modelling migration in terms of age/gender/marital status/household membershipMarital status modelling?

Integration of estimates of households with dwelling counts