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Transcript of Centre for Market and Public Organisation Parental income and child outcomes Paul Gregg, Carol...
Centre for Market and Public Organisation
Parental income and child outcomesPaul Gregg, Carol Propper and Elizabeth Washbrook
Avon Local Group of the Royal Statistical Society Meeting
Bristol, 26th May 2009
Family income and child outcomes Drivers of the developmental deficits of low income children are of interest to academics and
policymakers Lifecycle models of human capital formation (Cunha and Heckman 2007; Carneiro and Heckman
2003) Labour reforms to tax credits, child care and early education, child benefit, maternity leave (e.g.
Brewer 2007)
Developmental outcomes in childhood are related to multiple aspects of adult well-being and have long term social consequences Cognitive and educational outcomes – IQ, test scores, grades Non-cognitive and socio-emotional outcomes – behavior, self-concept, motivation, attention Physical health – obesity and poor nutrition, asthma, injuries, illnesses
Adult outcomes associated with at least one class of child outcome Years of schooling, qualifications, employment and earnings, mental health, life expectancy and
morbidity, antisocial and risky behavior, crime, fertility
This paper
Uses data from an unusually rich birth cohort dataset to compare the income gradients in six developmental outcomes in mid-childhood The income gradient is the unconditional association between income and the outcome – one
broad measure of social inequality
Develops a descriptive decomposition method to give an overview of the underlying associations that give rise to the observed income gradients We estimate the portion of the observed gradients predicted by income-related differences in a
wide range of potential explicators
Estimates can be interpreted in the light of two approaches taken in the literature Reduced form OLS studies of the relationship between child poverty and outcomes (e.g. Duncan
and Brooks-Gunn 1997). [Precursors to studies on the causal effects of income, e.g. Blau 1999; Dahl and Lockner 2005.]
Correlational SEM studies of the mediators between family income and child outcomes (Guo and Harris 2000; Yeung et al., 2002)
The contribution of descriptive estimates The associations identified in our estimates are not causal. They do not, for example, adjust for
reverse causation or the influence of unobservable third factors such as inherited ability
Causal approaches provide crucial evidence on parts of the puzzle of why low income children fall behind The effect of increasing cash benefits for low income families The effects specific factors on outcomes (intervention programmes, smoking, birth order, inherited
characteristics)
But causal studies relying on specific mechanisms cannot give an overview of relative importance of all the potential factors that drive the intergenerational persistence of poverty. Single and teen parenthood, low parental education, worklessness and deprived neighborhoods –
control variables Parental stress and depression, social connections, child care experiences, unhealthy environments,
parenting behaviors - mediators
Contribution of our paper What are the upper bounds on the effects of interventions targeted to specific
factors in terms of reducing social inequality in child well-being?
Conclusions depend on whether we focus on a single or multiple classes of outcomes. Some factors are associated with all three types of outcome. Examples are breast
feeding and child nutrition, discipline and maternal locus of control. Some factors are strongly associated with some outcomes but not others. Maternal
social networks and parental smoking explain the non-cognitive and health gradients but not the cognitive.
Some factors have opposing associations with certain aspects of development. Lack of car ownership and poor housing are associated with lower risk of obesity; lower attendance at center-based child care is associated with fewer behavioral problems
Data: The ALSPAC cohort
9476 children born in Bristol and the surrounding regions (Avon) in 1991/2
Population 1 million, mixture of rural, suburban and urban, broadly nationally representative
Census of pregnant mothers rather than random sample, very high frequency
Mother-completed postal questionnaires Teacher-completed postal questionnaires Hands-on assessments in clinics at ages 7, 8 and 9 Matched to Key Stage national school test results from the National Pupil Database
Outcome measuresCognitive
IQ at age 8. WISC-III UK. Academic achievement at age 7. Key Stage 1 national school tests (KS1). Reading, writing and mathematics.
Non-cognitiveLocus of control at age 8. Child completed. Short form of Nowicki-Strickland Internal-External scale for children.Self esteem at age 8. Child completed. Short form of Harter’s Self Perception Profile for Children.Behavioral problems at age 7. Teacher rated. Strengths and Difficulties Questionnaire. Hyperactivity, peer relations, conduct problems, emotional problems.
HealthFat mass at age 9. Total body dual energy X-ray absorptiometry (DXA scans).
The income gradient
Oij = δYi + eij eij ┴ Yi
Income(Y)
ChildOutcome j
(Oj)
δ
Oij is the jth outcome of the ith childYi is the log of average disposable equivalised household income at child age 3 and 4 in 1995 priceseij is an orthogonal error termAll outcomes standardised to mean 100, SD 10.In presentation, the signs of the coefficients are adjusted, such that positive coefficients represent more beneficial outcomes in all cases.
Income gradients in outcomes in middle childhood
88
90
92
94
96
98
100
102
104
106
108
30 80 130 180 230 280 330 380 430 480 530 580 630
Equivalised disposable weekly household income age 3/4 (1995 GBP)
Sco
re (
mea
n 1
00,
SD
10)
IQ (5.85)
KS1 (5.46)
Locus of control (3.30)
Self esteem (1.71)
Behavior (2.01)
Fat mass (1.34)
p < 0.01 for all gradients
Control variablesHousehold demographics: Single parenthood, siblings, mother’s ageLabor market status: Mother’s and partner’s employment and occupational classEducation: Mother’s, partner’s and maternal grandparents’ qualificationsNeighborhood: Local deprivation (IMD for ward at birth), social housing
Mediating variablesMaternal psychosocial functioning: Anxiety/depression, weighted life events, financial difficulties, parental relationship, frequency of smacking, social networks, locus of controlPreschool childcare: Type and intensity, between birth and age 3, between age 3 and school entryHealth & health behaviours: Birth weight and gestation, parental smoking, breastfeeding, diet at age 3Home learning environment: Books and toys, maternal teaching, educational outings, mother’s and partner’s reading and singing with childPhysical home environment: Car ownership, garden, noise, crowding, damp/mouldSchool quality and mix: Fixed effects
Decomposing the income gradient
Oij = δYi + eij eij ┴ Yi
Income(Y)
ChildOutcome j
(Oj)
δ
Modelling framework
Income(Y)
Controls(C)
e.g. parental education,
family structure
Mediators(M)
e.g. home learning
environment, diet
ChildOutcome j
(Oj)γj
θj
πj
β
λα
(1) Oij = γjMi + θjCi + πjYi + μij μij ┴ Mi, Ci, Yi
Modelling framework
Income(Y)
Controls(C)
e.g. parental education,
family structure
Mediators(M)
e.g. home learning
environment, diet
ChildOutcome j
(Oj)γj
θj
πj
β
λα
(2) Mi = βCi + λYi + ηi ηi ┴ Ci, Yi
Modelling framework
Income(Y)
Controls(C)
e.g. parental education,
family structure
Mediators(M)
e.g. home learning
environment, diet
ChildOutcome j
(Oj)γj
θj
πj
β
λα
(3) Ci = αYi + νi νi ┴ Yi
Modelling framework
Income(Y)
Controls(C)
e.g. parental education,
family structure
Mediators(M)
e.g. home learning
environment, diet
ChildOutcome j
(Oj)γj
θj
πj
β
λα
(4) Oij = (γjβα + γjλ + θjα + πj) Yi + error
= δjYi + eij
Modelling framework
δj = γjβα + γjλ + θjα + πj
The unconditional income gradient can be written as the sum of a set of path coefficients.
Each path coefficient is the product of the partial effects of one variable on another. If any link in the chain is zero, the path coefficient will be zero.
Path coefficients calculated by multiplying and summing the OLS coefficients from the underlying regressions. Standard errors estimated by bootstrapping with 200 repetitions.
Path coefficients can be combined in different ways to give alternative decompositions of the income gradient.
Income gradient decompositions - summary
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
A. Total mediators (sum i to vi) 1.87** 1.86** 1.78** 0.78* 1.27* 0.79* i. Maternal psychosocial functioning 0.66** 0.56** 0.48* 0.68** 1.23** 0.50** ii. Pre-school child care 0.16 0.07 0.44** -0.16 -0.28 0.20 iii. Health & health behaviors 0.38** 0.59** 0.43** 0.03 0.66** 0.72** iv. Home learning environment 0.54** 0.60** 0.33* 0.37** 0.21 -0.26* v. Physical home environment 0.05 0.10 -0.01 -0.26 -0.31 -0.40* vi. School fixed effects 0.08 -0.07 0.10 0.11 -0.23 0.05 B. Total unmediated controls (sum vii to x) 3.08** 2.84** 1.43** 0.62* 0.67* 0.66* vii. Household demographics 0.29† 0.12 0.25 0.06 -0.09 -0.17 viii. Labor market status 0.17 0.51** 0.17 -0.01 0.06 -0.03 ix. Education 2.10** 1.44** 0.94** 0.56** 0.48† 0.54** x. Neighborhood 0.54** 0.79** 0.07 0.00 0.23 0.32† C. Total unmediated income 0.90* 0.76** 0.09 0.31 0.07 -0.11 Unconditional income gradient (A+B+C) 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113
Income gradient decompositions - summary
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
A. Total mediators (sum i to vi) 1.87** 1.86** 1.78** 0.78* 1.27* 0.79* i. Maternal psychosocial functioning 0.66** 0.56** 0.48* 0.68** 1.23** 0.50** ii. Pre-school child care 0.16 0.07 0.44** -0.16 -0.28 0.20 iii. Health & health behaviors 0.38** 0.59** 0.43** 0.03 0.66** 0.72** iv. Home learning environment 0.54** 0.60** 0.33* 0.37** 0.21 -0.26* v. Physical home environment 0.05 0.10 -0.01 -0.26 -0.31 -0.40* vi. School fixed effects 0.08 -0.07 0.10 0.11 -0.23 0.05 B. Total unmediated controls (sum vii to x) 3.08** 2.84** 1.43** 0.62* 0.67* 0.66* vii. Household demographics 0.29† 0.12 0.25 0.06 -0.09 -0.17 viii. Labor market status 0.17 0.51** 0.17 -0.01 0.06 -0.03 ix. Education 2.10** 1.44** 0.94** 0.56** 0.48† 0.54** x. Neighborhood 0.54** 0.79** 0.07 0.00 0.23 0.32† C. Total unmediated income 0.90* 0.76** 0.09 0.31 0.07 -0.11 Unconditional income gradient (A+B+C) 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113
Income gradient decompositions - summary
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
A. Total mediators (sum i to vi) 1.87** 1.86** 1.78** 0.78* 1.27* 0.79* i. Maternal psychosocial functioning 0.66** 0.56** 0.48* 0.68** 1.23** 0.50** ii. Pre-school child care 0.16 0.07 0.44** -0.16 -0.28 0.20 iii. Health & health behaviors 0.38** 0.59** 0.43** 0.03 0.66** 0.72** iv. Home learning environment 0.54** 0.60** 0.33* 0.37** 0.21 -0.26* v. Physical home environment 0.05 0.10 -0.01 -0.26 -0.31 -0.40* vi. School fixed effects 0.08 -0.07 0.10 0.11 -0.23 0.05 B. Total unmediated controls (sum vii to x) 3.08** 2.84** 1.43** 0.62* 0.67* 0.66* vii. Household demographics 0.29† 0.12 0.25 0.06 -0.09 -0.17 viii. Labor market status 0.17 0.51** 0.17 -0.01 0.06 -0.03 ix. Education 2.10** 1.44** 0.94** 0.56** 0.48† 0.54** x. Neighborhood 0.54** 0.79** 0.07 0.00 0.23 0.32† C. Total unmediated income 0.90* 0.76** 0.09 0.31 0.07 -0.11 Unconditional income gradient (A+B+C) 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113
Income gradient decompositions - summary
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
A. Total mediators (sum i to vi) 1.87** 1.86** 1.78** 0.78* 1.27* 0.79* i. Maternal psychosocial functioning 0.66** 0.56** 0.48* 0.68** 1.23** 0.50** ii. Pre-school child care 0.16 0.07 0.44** -0.16 -0.28 0.20 iii. Health & health behaviors 0.38** 0.59** 0.43** 0.03 0.66** 0.72** iv. Home learning environment 0.54** 0.60** 0.33* 0.37** 0.21 -0.26* v. Physical home environment 0.05 0.10 -0.01 -0.26 -0.31 -0.40* vi. School fixed effects 0.08 -0.07 0.10 0.11 -0.23 0.05 B. Total unmediated controls (sum vii to x) 3.08** 2.84** 1.43** 0.62* 0.67* 0.66* vii. Household demographics 0.29† 0.12 0.25 0.06 -0.09 -0.17 viii. Labor market status 0.17 0.51** 0.17 -0.01 0.06 -0.03 ix. Education 2.10** 1.44** 0.94** 0.56** 0.48† 0.54** x. Neighborhood 0.54** 0.79** 0.07 0.00 0.23 0.32† C. Total unmediated income 0.90* 0.76** 0.09 0.31 0.07 -0.11 Unconditional income gradient (A+B+C) 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113
Income gradient decompositions – disaggregated mediators
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
i. Maternal psychosocial functioning 0.66** 0.56** 0.48* 0.68** 1.23** 0.50** Of which: Maternal anxiety/depression 0.05 0.06† 0.12† 0.14* 0.12† -0.07 Life event shocks -0.06 -0.02 0.00 0.05 0.22** 0.09† Subjective financial distress 0.14 0.13 -0.05 0.18 0.02 0.13 Quality of parental relationship -0.03 -0.14** -0.09 -0.06 -0.09 0.01 Frequency of smacking at 3 0.11** 0.05* 0.11** 0.18** 0.13* 0.00 Maternal social networks 0.08 0.07 0.06 0.08 0.40** 0.15† Maternal locus of control 0.35** 0.40** 0.34** 0.11 0.43** 0.19† Unconditional income gradient 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113
Income gradient decompositions – disaggregated mediators
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
iii. Health & health behaviors 0.38** 0.59** 0.43** 0.03 0.66** 0.72** Of which: Health at birth 0.04† 0.04* 0.01 0.01 0.00 -0.03 Smoking -0.17* 0.01 0.07 0.01 0.39** 0.29** Breast feeding 0.21** 0.14** 0.17* -0.01 0.12 0.17** Eating patterns at 3 0.30** 0.39** 0.17 0.02 0.14 0.28* Unconditional income gradient 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113
Income gradient decompositions – disaggregated mediators
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
iv. Home learning environment 0.54** 0.60** 0.33* 0.37** 0.21 -0.26* v. Physical home environment 0.05 0.10 -0.01 -0.26 -0.31 -0.40* Of which: Car ownership -0.08 0.06 -0.04 -0.11 0.09 -0.29** Has garden 0.02 -0.05 0.00 -0.07 -0.07 0.02 Noise 0.00 0.02 0.02 0.02 0.08 -0.02 Crowding 0.14 0.08 0.14 -0.05 -0.23 0.02 Damp/condensation/mould -0.04 -0.01 -0.12† -0.05 -0.18† -0.14* Unconditional income gradient 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113
Income gradient decompositions – mediators of income and controls
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
A. Total mediated controls 1.40** 1.38** 1.25** 0.14 0.53 0.69** B. Total mediated income 0.47* 0.48** 0.53* 0.63** 0.73† 0.09 C. Total mediators (A+B) 1.87** 1.86** 1.78** 0.78* 1.27* 0.79*
D. Total unmediated controls 3.08** 2.84** 1.43** 0.62* 0.67* 0.66* E. Total unmediated income 0.90* 0.76** 0.09 0.31 0.07 -0.11 F. Total unmediated (D+E) 3.99** 3.61** 1.52** 0.93† 0.75 0.55
G. Total controls (A+D) 4.49** 4.23** 2.68** 0.77* 1.21** 1.36** H. Total income (B+E) 1.36** 1.23** 0.62 0.94* 0.80 -0.02 I. Unconditional income gradient (G+H) 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113
Income gradient decompositions – mediators of income and controls
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
A. Total mediated controls 1.40** 1.38** 1.25** 0.14 0.53 0.69** B. Total mediated income 0.47* 0.48** 0.53* 0.63** 0.73† 0.09 C. Total mediators (A+B) 1.87** 1.86** 1.78** 0.78* 1.27* 0.79*
D. Total unmediated controls 3.08** 2.84** 1.43** 0.62* 0.67* 0.66* E. Total unmediated income 0.90* 0.76** 0.09 0.31 0.07 -0.11 F. Total unmediated (D+E) 3.99** 3.61** 1.52** 0.93† 0.75 0.55
G. Total controls (A+D) 4.49** 4.23** 2.68** 0.77* 1.21** 1.36** H. Total income (B+E) 1.36** 1.23** 0.62 0.94* 0.80 -0.02 I. Unconditional income gradient (G+H) 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113
Income gradient decompositions – mediators of income and controls
Cognitive Non-cognitive Health
Path coefficient IQ KS1 Locus control
Self esteem
Behav- ior
Fat mass
Total income (conditional on controls) 1.36** 1.23** 0.62 0.94* 0.80 - Of which mediated by:
Maternal psychosocial functioning 0.24† 0.14 0.15 0.41** 0.77** 0.35* Pre-school childcare - - 0.21* - -0.22 - Health & health behaviors - 0.14** - 0.10* 0.13 - Home learning environment 0.13† 0.13* - 0.13† 0.11 -0.14* Physical home environment - - - -0.10 -0.11 -0.17* School fixed effects - - - 0.14 - -
Unmediated 0.90* 0.76** - 0.31 - -0.11 Unconditional income gradient 5.85** 5.46** 3.30** 1.71** 2.01** 1.34** Observations 5708 8727 5390 5857 3294 6113 Path coefficients <0.1 in magnitude and insignificant at the 10% level not shown.
Conclusions
Our accounting exercise produces a number of findings in line with previous research Income gradients are steeper for cognitive outcomes than for non-
cognitive or health outcomes The estimated effect of income drops steeply when other forms of socio-
economic disadvantage are controlled Mediators between income and outcomes are many and diffuse Less cognitive stimulation in the home helps to account for the cognitive
deficits of low income children; poorer maternal psychosocial functioning helps to account for their behavioral deficits
Conclusions
Our comparative approach provides new insights that may be missed in more narrowly-focused studies Maternal psychosocial functioning and health-related behaviors appear
as important as the home learning environment in accounting for the cognitive deficits of low income children
Some factors have a modest role to play in explaining multiple gradients (e.g. breast feeding, discipline)
A focus only on cognitive outcomes may miss the adverse consequences of certain factors for other dimensions of development (e.g. smoking, social networks)
Not everything that high income parents do is necessarily good for their children. Behaviors that promote cognitive development (learning-focused environments) could have adverse consequences for physical health