Household Projections for Northern Ireland 9 th September 2009

Household Projections for Northern Ireland

9th September 2009

Dr David Marshall & Dr Jos IJpelaar

Demography & Methodology BranchNorthern Ireland Statistics & Research Agency

Introduction

• 2006-based Household projections

• Health Card Registration Data– Persons/household information– Use for household propensities– Use for household transition indicators

• Implementation in 2008-based projections

2006-Based

Household Projections

• Housing Growth Planning

• Household composition trend 1991-2001 Census

• First published in January 2005

• Updated using 2006-based population projections; in March 2008

NI Household Projections

Population Projections

1991 Census

Household Projections

Mid-Year Population Estimates

Fertility, mortality

and migration assumptions

Registered Births

Registered Deaths

Estimated Migration

2001 Census

Schematic Projection Process

Householdformation

assumptionsOther Sources

Household Membership Probabilities

• 18 Household categories– seven sizes (1 - 7+ persons) and three types (adults

only, 1 adult with children, 2+ adults with children)

• 14 Age groups

• Projected probabilities for membership of each household category for each age-sex group

• Constant age-sex probability of being resident in communal

0.0

0.2

0.4

0.6

0.8

1.0

1991 2001 2011 2021 2031

Methodology: 2-Point Exponential

10

1991

1991

20011991 1

111

i

i p

ppp

10

1991

1991

20011991

i

i p

ppp

For p2001 >= p1991

For p2001 < p1991

Some special cases

• Constant probabilities for under 19s– Evidence that the 1991-2001 trend of smaller families

and more single parent households does not continue in the period 2001-06

• Complete “households with children” with adults, remaining adults distributed over childless household types

• Complete couple households with females aged 75+ from single households

Population Projection by age and sex (2011)

15,000 10,000 5,000 0 5,000 10,000 15,000

0

10

20

30

40

50

60

70

80

Age

(yea

rs)

Persons

Male

Female


15,000 10,000 5,000 0 5,000 10,000 15,000

0

10

20

30

40

50

60

70

80

Age

(yea

rs)

Persons

Male HH

Male Com

Female HH

Female Com

Subtractprojected communal population


15,000 10,000 5,000 0 5,000 10,000 15,000

0

10

20

30

40

50

60

70

80

Age

(yea

rs)

Persons

Other HH

1+child

2+child

Communal

Children in householdswith children


15,000 10,000 5,000 0 5,000 10,000 15,000

0

10

20

30

40

50

60

70

80

Age

(yea

rs)

Persons

Other HH

1+child

2+child

Communal

Completehouseholds-with-childrenwith adults


15,000 10,000 5,000 0 5,000 10,000 15,000

0

10

20

30

40

50

60

70

80

Age

(yea

rs)

Persons

1 person2 adult3+ adult1+child2+childCommunal

Allocateremainingadults overchildlesshouseholds


15,000 10,000 5,000 0 5,000 10,000 15,000

0

10

20

30

40

50

60

70

80

Age

(yea

rs)

Persons

1 person2 adult3+ adult1+child2+childCommunal

Completingelderly couplehouseholds

Health Card

Registration Data

NI Health Card Data

• 1.817M health records (2008)

• 1.775M population estimate (2008)

• Primary source for official migration estimates

• Date of Birth, Sex & Address

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,0000

-4

'5-9

'10

-14

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

+

Census (M) Health Card (M) Census (F) Health Card (F)

Health Card (2001) vs. Census Household population by age and sex

NI Health Card Data

• Using address database to allocate unique address identifier

• Household definition: all persons at same address

• Communal establishments: exclude all addresses with 15+ persons

NI Health Card Data - Issues

• Accuracy depends on notification

• Incomplete address information

• Persons not families

• Armed Forces

• List Inflation

PersonID Age Sex HseholdID Year

P0001 24 F HH1 2001

P0001 25 F HH1 2002

P0002 26 M HH1 2001

P0002 27 M HH1 2002

P0003 0 F HH1 2002

P0003 51 M HH2 2001

P0003 52 M HH3 2002

P0004 79 F HH4 2001

P0004 80 F HH4 2002

Health Card Registration Data - Example

0%

20%

40%

60%

80%

100%0

-4

'5-9

'10

-14

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

+

Census - single adult with chldren

Census - 2+ adults with children

2001 Census Households with children, Females

0%

20%

40%

60%

80%

100%0

-4

'5-9

'10

-14

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

+

Health Cards - single adult Health Cards - 2+ adults

Census - single adult Census - 2+ adults

Health Card (2001) vs. Census Households with children, Females

0%

10%

20%

30%

40%

50%1

5-1

9

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

+

2001 20042006 2008

Health Card Data, 2001-2008Females in 2 adult households (without children)

Household Transition

• Age-sex probability of persons in household type A in year t being in household type A,B,C… in year t+1

• Does not take account of other persons in household

• Cannot be done using Census data

Household Transitions Example:Household type in 2008 for females

who were aged 25-29 in childless 2-adult households in 2007

2 adults

1 adult

3+ adults

2+ adults & child

1 adult & child

Left NI

Household Type 2008

1 adult 2 adults 3+ adults1 adult &

child2+ adult

& child

Household Type 2007

1 adult 60% 15% 5 % 12 % 8 %

2 adults 8 % 63 % 10 % 2 % 16 %

3+ adults

5 % 7 % 80 % 9 % 7 %

1 adult & child

2 % 1 % 0 % 79 % 19 %

2+ adult & child

2 % 2 % 4 % 6 % 85 %

Household Transitions Example (2)Females aged 25-29yrs, 2007-8 (excl. migration)

0%

10%

20%

30%

40%

50%200

8

200

9

201

0

201

1

201

2

201

3

201

4

201

5

201

6

201

7

201

8

201

9

202

0

202

1

202

2

202

3

202

4

202

5

202

6

202

7

202

8

202

9

203

0

203

1

1 adult 2 adults 3+ adults

1 adult & child 2+ adult & child

Household Transitions Example (3)Females 25-29yrs, projections with transition matrix

Left NI

2007

Stayed

2007

Stayed

2008

Arrived in NI

2008

1 adult 12% 11% 10% 14%

2 adults 14% 12% 12% 17%

3+ adults 39% 33% 29% 35%

1 adult & child

9% 12% 13% 5%

2+ adult & child

26% 32% 35% 28%

Total 100% 100% 100% 100%

Household Type - MigrationFemales aged 25-29yrs, 2007 and 2008

Using Health Card

Registration Data in

2008-based Household Projections

Census trend vs. Health Card dataMales aged 4-15yrs, 1 adult & 1 child household

0%

1%

2%

3%

4%

5%

6%

7%

8%

199

1

199

3

199

5

199

7

199

9

200

1

200

3

200

5

200

7

200

9

201

1

201

3

201

5

201

7

201

9

202

1

Census 2pt.Exp.Census trend


0%

1%

2%

3%

4%

5%

6%

7%

8%

199

1

199

3

199

5

199

7

199

9

200

1

200

3

200

5

200

7

200

9

201

1

201

3

201

5

201

7

201

9

202

1

Census 2pt.Exp.Census trend Health Cards


0%

1%

2%

3%

4%

5%

6%

7%

8%

199

1

199

3

199

5

199

7

199

9

200

1

200

3

200

5

200

7

200

9

201

1

201

3

201

5

201

7

201

9

202

1

Census 2pt.Exp.Census trendHealth Cards Health Cards (calibr)Health Card - linear trend

Further Developments

• 2008-based household projections will be published in Spring 2010– Health Card data for projecting propensities

• Review methodology– Introduce cohort analysis with transition matrices– Constrain transitions with projected births, deaths

and migration– Alternative household types?

• Explore use of alternative data sources– Longitudinal Study?

Household Projections for Northern Ireland

9th September 2009

http://www.nisra.gov.uk/demography/default.asp21.htm

Dr David Marshall & Dr Jos IJpelaar

Demography & Methodology BranchNorthern Ireland Statistics & Research Agency

Documents

Household Projections for Northern Ireland 9 th September 2009