Education and the contemporary ‘baby boom’: Evidence from the Northern Ireland Longitudinal Study

The data

Education and the contemporary ‘baby boom’: Evidence from the Northern Ireland Longitudinal

Study

Patrick McGregor Patricia McKee

“Predicting Short Run Changes in Fertility in Northern Ireland”

a project funded by

The authors are grateful to the NILS team at NISRA for their assistance

2

Education and the contemporary ‘baby boom’: Evidence from the Northern Ireland Longitudinal Study

• Overview• Education and fertility• The NILS• The data• The statistical model• Results• Conclusion

Overview 3

A baby-boom fuelled by rising fertility rates and immigration has pushed the population of the United Kingdom to more than 61 million for the first time.

The Times, 28 August 2009

The data 4

Total Births

Age Specific Fertility Rates

20000

22000

24000

26000

28000

30000

32000

1977 1982 1987 1992 1997 2002 2007

year

birt

hs r

egis

tere

d

0

25

50

75

100

125

150

175

200

1977 1982 1987 1992 1997 2002 2007

Ag

e-s

pe

cific

fert

ility

ra

te

15-19 20-24 25-29 30-34 35-39 40-44

Fertility in Northern Ireland

Education and fertility 5

Education and fertility

Static economic analysis

Max ST

Children assumed to be normal ‘goods’ so: but possibly or possibly not!

The home production framework allows the cost of children to be expressed as a function of the parents’ wages and their respective shares in the costs of producing child quality

sqnUU ,,sc snqI

0 qn 0n

Education and fertility 6

Dynamic economic analysis The ‘user cost’ of a child now is a function of a

sequence of prices such as the female wage rate

The optimal profile of a woman’s stock of human capital will be jointly determined with the timing of the births of her children.

Any empirical analysis should permit the demographic profile to vary with educational attainment

The NILS 7

The NILS

• The NILS potential mothers: those women with health card registrations, aged 16-44 years and whose DOB is one of the 104 in the systematic sample

• Registrations downloaded biannually and constitute potential panel members

• Details of any birth to a NILS mother are forwarded by the GRO to the NILS

• 2001 Census: An attempt is made to link the Census details of all NILS mothers

The NILS 8

Population on Census Day, 2001

Total Population

Census 1,685,267 (4.84% Imputed)

BSO 1,768,473 (4.94% list inflation)

Women in NILS aged 16-44 years

Census 101,034 ( Census x 104/365.25)

BSO 107,874

list inflation 6,840 (6.3%)

Expected imputed census records 4,890 (101,034 x 0.0484)

Fertility Panel with census records 93,601

BSO – FP 14,273

Mismatch = 14,273 – 6,840 – 4,890 = 2,543

The data 9

Year N % pattern01 5083 3.5 100000001-02 5167 3.6 110000001-03 5771 4.0 111000001-04 4523 3.1 111100001-05 4804 3.3 111110001-06 4451 3.1 111111001-07 76878 53.0 111111102-07 4416 3.1 011111103-07 4353 3.0 001111104-07 4649 3.2 000111105-07 5067 3.5 000011106-07 5796 4.0 0000011 07 6504 4.5 0000001

Presence of women in the Fertility Panel:the effect of Age

born 1957 1977 1978 1991age 2001 44 24 23 10age 2007 50 30 29 16

The fertility panel essentially is the 1957 – 77 cohort and ignores the 1978 – 91 cohort due to the absence of educational information

The data 10

Sources of Information available for the NILS

Fertility Panel

101

Census 91

4,653

7,019

Census 01

GRO

BSO

61,263

24,041

32,960

530

26,710

The data 11

Sources of Parity in the Fertility Panel

Parity from Freq. PercentCensus - offspring 116,327 74.0GRO births 10,141 6.591 census 6,432 4.1Count births 97-01 178 0.1Census + n of births 158 0.1Missing 24,041 15.3

Total Women 157,277 100.0

The data 12

Educational Qualifications

• Level 0

• Level 1

• Level 2

• Level 3

• Level 4

• Level 5

No qualifications

GCSE grade D-G; 1-4 CSEs grade 1;

1-4 ‘O’ level passes; NVQ level 1

5+ CSEs grade 1; 5+ GCSEs grade A-C;

5+ ‘O’ level passes; NVQ level 2

2+ ‘A’ levels; 4+ AS levels;

NVQ level 3 or GNVQ Advanced

First degree; NVQ level 4; HNC ; HND

Higher degree; NVQ level 5

The data 13

2325

20

10

22

0

5

10

15

20

25

30

no quals level 1 level 2 level 3 level 4/5

Education level

Pro

port

ion

of s

ampl

e

The Distribution of Educational Attainment

The data 14Source: 2001 Census

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

19

81

19

82

19

83

19

84

19

85

19

86

19

87

19

88

19

89

19

90

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

year

pro

po

rtio

n

none lev 1 lev 2 lev 3 uni deg

Distribution of Educational Attainment by Year that Woman was aged 24

The data 15

0

100

200

300

400

500

600

1997 1999 2001 2003 2005 2007

Year

Gro

ss

We

ek

ly p

ay

(£

)

63.0

64.0

65.0

66.0

67.0

68.0

Act

ivit

y R

ate

Q1 median Q3 Activity Rate

Women in the Labour Market

Source: DETINI

The data 16

First Birth

22

25

28

31

34

1997 1999 2001 2003 2005 2007

Year

mea

n a

ge

of

mo

ther

no quals level 1

Third Birth

22

25

28

31

34

1997 1999 2001 2003 2005 2007

Yearm

ean

ag

e o

f m

oth

erlevel 4/5

Second birth

22

25

28

31

34

1997 1999 2001 2003 2005 2007

Year

mea

n a

ge

of

mo

ther

level 2 level 3

Mean Age of Mother at Time of Birth

The Statistical Model 17

The Statistical Model

• Raftery, AE, Lewis, SM and Aghajanian, A (1995).• Demand or Ideation? Evidence from the Iranian

Marital Fertility Decline, Demography, vol. 32.• Data: 1977 Iran Fertility Survey• “ each woman-year of exposure is treated as a

separate case” • Five clocks:

– Age Period Cohort Parity Duration

The Statistical Model 18

The Logit Model

iiiii

iiiiii

XEDUCATIONECONOMIC

TIMENSINTERACTIODURATIONPARITYAGEB

/

76

54321*

0*0

0*1

ii

ii

BifB

BifB

EDUCATION includes interactions with PARITY, DURATION and TIME so demographic profile can vary with educational attainment

TIME captures the change in quantum for women aged > 23

Results 19

Demographic

age 237.053age2 -309.685age3 182.198age4 -41.369

par1 2.078par2 2.595par3 2.161pargt3 0.899

dur1 -3.974dur2 -2.483dur3 -1.661dur4 -1.783dur5 -1.540

Demographic interactions

agepar1 -1.420agepar2 -2.663agepar3 -2.441agepargt3 -1.341

agedur1 3.512agedur2 3.162agedur3 2.442agedur4 2.283agedur5 1.927

Education level01constant 0.651quality -2.003timetrend -0.173quality*tt 0.343

Demographic par0 -0.384par1 -0.386par2 -0.178par3 -0.096

dur1 0.046dur2 -0.234dur3 -0.195dur4 -0.091dur5 -0.140durgt5 -0.03

Logit Regression Results Education level 45constant 1.438quality -5.470timetrend -0.145quality*tt 0.702

interactionspar0 -0.010par1 0.258par2 0.238par3 0.094

dur1 0.138dur2 0.484dur3 0.468dur4 0.557dur5 0.394durgt5 0.394

Timeyr2002 -0.457yr2004 -0.427yr2005 -1.473yr2006 -0.111timetrend 0.667

Economicfwage-1 -1.423factivityrate-1 -0.971Interest-1 0.244

Othercatholic 0.169constant -2.758

Results 20

Demographic

age 237.053age2 -309.685age3 182.198age4 -41.369

par1 2.078par2 2.595par3 2.161pargt3 0.899














The demographic profile of the base educational category is well determined with parity=0 and durgt5 base

Results 21

Work and childbearing tend to be separate rather than combined activities; wage rate not significant although divided by quartiles; interest rate?

Demographic

age 237.053age2 -309.685age3 182.198age4 -41.369

par1 2.078par2 2.595par3 2.161pargt3 0.899














Results 22




There is a fluctuating increase in the quantum of those 24 and over

Demographic

age 237.053age2 -309.685age3 182.198age4 -41.369

par1 2.078par2 2.595par3 2.161pargt3 0.899











Results 23




For those from Northern Ireland

Demographic

age 237.053age2 -309.685age3 182.198age4 -41.369

par1 2.078par2 2.595par3 2.161pargt3 0.899











Results 24




The differential quantum effect of education for those aged >23 in the 1957 – 77 cohort

Demographic

age 237.053age2 -309.685age3 182.198age4 -41.369

par1 2.078par2 2.595par3 2.161pargt3 0.899











Results 25







The differential tempo effect of education for those aged >23 in the 1957 – 77 cohort

Demographic

age 237.053age2 -309.685age3 182.198age4 -41.369

par1 2.078par2 2.595par3 2.161pargt3 0.899








Results 26

Marginal Effects

0,1ˆ1,1ˆ, educXBPeducXBPME iiiiieduc

Where is the vector of values of all the explanatory variables except for educ

iX

For ith woman:

Educational variables are ordered:

noqual base degree

% sample 48 30 22

The marginal effect is taken as the mean of individual marginal effects over the particular category and the base

The data 27

Parity 0 1 2 3 mean par at 24No quals 0.043 0.084 0.039 0.033 0.98others 0.066 0.132 0.049 0.037 0.51Degree 0.069 0.193 0.073 0.050 0.10

Table: Probability of Birth 2001-7

Marginal Effect of Education

No qualifications

-0.05

0

0.05

0.1

0.15

24 26 28 30 32 34 36 38 40 42 44

Age

Mar

gin

al e

ffec

t

Degrees

-0.05

0

0.05

0.1

0.15

24 26 28 30 32 34 36 38 40 42 44

Age

Mar

gin

al e

ffec

t

par=0 tt only

par=1 tt only

par=2 tt only

par=0 + dem

par=1 + dem

par=2 + dem

Results 28

Conclusions

• The total marginal effect of educational attainment , including both quantum and tempo effects, is almost always positive

• It peaks at 0.16 for women aged 33 with parity = 1 for the degree case; for parity = 0 the marginal effect is about one third of this

• In the degree case the quantum effects are negative up to age 28 possibly reflecting the decline in degree ‘quality’

• For the poorly qualified the pattern is similar, except that the peak for parity = 1 is earlier, at 30 and smaller, at 0.11

• For most ages, the marginal effect is greater for parity 2 than 0

Results 29

parity = 0

0

10

20

30

40

50

60

70

80

90

100

24 26 28 30 32 34 36 38 40 42 44

age

%

noqual

middle

degree

parity = 1

0

5

10

15

20

25

30

35

40

24 26 28 30 32 34 36 38 40 42 44

age

%

noqual

middle

degree

parity = 2

0

5

10

15

20

25

30

35

40

24 26 28 30 32 34 36 38 40 42 44

age

%

noqual

middle

degree

parity = 3

0

5

10

15

20

25

30

35

40

24 26 28 30 32 34 36 38 40 42 44

age

%

noqual

middle

degree

Parity Proportions by Age and Education

The data 30

Births and Birth Events

N of births Freq. Percent

0 371,113 84.521 66,944 15.252 995 0.23

3+ 24 0.01

Total 439,076 100

In the analysis birth events rather than births per se are examined

Documents

Education and the contemporary ‘baby boom’: Evidence from the Northern Ireland Longitudinal Study