Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
THE HEALTH EFFECTS OF EARLY
CHILDHOOD INTERVENTIONS
Gabriella Conti
University College London, IFS and NBER
James J. Heckman, Seong Moon, Rodrigo Pinto
University of Chicago
DAHR Seminar
April 10, 2014
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
1 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Motivation
Motivation
I A consolidated body of evidence documents the importance of early
life conditions as determinants of health.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
2 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Motivation
Motivation
I A consolidated body of evidence documents the importance of early
life conditions as determinants of health.
I The bulk of health care costs result from relatively few individuals
with multiple chronic conditions.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
2 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Motivation
Motivation
I A consolidated body of evidence documents the importance of early
life conditions as determinants of health.
I The bulk of health care costs result from relatively few individuals
with multiple chronic conditions.
I NCDs (noncommunicable diseases) are the main cause of death in
both developed and developing countries.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
2 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Motivation
Motivation
Most of current policy interventions focus on managing these conditions
or attempting behavior change in adults.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
2 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Motivation
Motivation
But such conditions are — at least in part
preventable.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
2 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
This Paper: Are Early Childhood Interventions an effective
strategy to prevent disease and promote health?
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
3 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
This Paper: Are Early Childhood Interventions an effective
strategy to prevent disease and promote health?
→ We examine the health effects of the two oldest and most widely
cited ECIs:
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
3 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
This Paper: Are Early Childhood Interventions an effective
strategy to prevent disease and promote health?
→ We examine the health effects of the two oldest and most widely
cited ECIs:
I the High/Scope Perry Preschool Project (PPP)
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
3 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
This Paper: Are Early Childhood Interventions an effective
strategy to prevent disease and promote health?
→ We examine the health effects of the two oldest and most widely
cited ECIs:
I the High/Scope Perry Preschool Project (PPP)
I the Carolina Abecedarian Intervention (ABC)
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
3 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
I IQ
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
I IQ
I problem behavior
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
I IQ
I problem behavior
I education
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
I
I
I
I
IQ
problem behavior
education
income
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
I
I
I
I
I
IQ
problem behavior
education
income
employment
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
I
I
I
I
I
I
IQ
problem behavior
education
income
employment
personal relationships
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
I
I
I
I
I
I
IQ
problem behavior
education
income
employment
personal relationships
→ inputs in a health production function
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
I
I
I
I
I
I
IQ
problem behavior
education
income
employment
personal relationships
→ inputs in a health production function
+ the ABC intervention also included a health component
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
This Paper
Why health effects of ECIs?
I High-quality ECIs targeted to disadvantaged children have been
shown to have longlasting effects on a variety of social and
economic outcomes (Heckman et al., QE [2010], AER [2013], Hines
et al., Science [2013], Nores and Barnett, EcEdRev [2010]):
I
I
I
I
I
I
IQ
problem behavior
education
income
employment
personal relationships
→ inputs in a health production function
+ the ABC intervention also included a health component
I but the health effects of ECIs have seldom been investigated
(Campbell et al., Science, 2014).
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Preview
Preview of Results
I Evidence
I PPP: males in the treated group have significantly lower prevalence
of unhealthy behaviors (esp. smoking) in adulthood.
I ABC: males in the treated group have significantly lower prevalence
of cardiovascular and metabolic risk factors in their mid 30s.
I Mechanisms
I PPP: significantly lower prevalence of problem behavior in childhood.
I ABC: significantly lower prevalence of overweight in childhood.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
5 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Preview
Outline of the Talk
I The PPP and ABC Interventions
I Methods
I Results
1
2
Evidence
Mechanisms
I Conclusions
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
6 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
(double RCT but ignore school-age
component for this talk)
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
(double RCT but ignore school-age
component for this talk)
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
(double RCT but ignore school-age
component for this talk)
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Where: Chapel Hill, North Carolina
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
(double RCT but ignore school-age
component for this talk)
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
(double RCT but ignore school-age
component for this talk)
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I Who: 98% African-American children
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
(double RCT but ignore school-age
component for this talk)
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I Who: 98% African-American children
I How: 50 w/y, 40 h/w (8 h/d)
social work visits
newsletter sent to parents
I How much: $9,604.30 (2010$) per
child/year
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
(double RCT but ignore school-age
component for this talk)
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I Who: 98% African-American children
I How: 50 w/y, 40 h/w (8 h/d)
social work visits
newsletter sent to parents
I How long: 5y (ages 0-5)
I How much: $9,604.30 (2010$) per
child/year
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP and ABC
ABC
PPP
I What: small RCT
(double RCT but ignore school-age
component for this talk)
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I Who: 98% African-American children
I How: 50 w/y, 40 h/w (8 h/d)
social work visits
newsletter sent to parents
I How long: 5y (ages 0-5)
I How much: $15,388 (2010$) per
child/year
Design
Conti, Heckman, Moon, Pinto
More
THE HEALTH EFFECTS OF ECIS
7 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Eligibility
Eligibility in the ABC and PPP Interventions
PPP
ABC
Requirements
Child IQ<85
No apparent biological conditions
Eligibility Criteria
Cultural Deprivation Scale
High-Risk Index
(1) Average Parent Education
(1) Absent Father
(2) No maternal relatives in area
(2) Father’s Occupation Rating
(3) Household Density
(3) Siblings below age-grade equiv.
(4) Welfare Payments
(5) Father’s work unstable or unskilled
(6) Mother’s or father’s IQ ≤85
(7) Sibling IQ≤90
(8) Social agency referral
(9) Family sought counseling or help
(10) Other special circumstances
(11) Mother’s education
(12) Father’s education
(13) Family income
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
8 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Eligibility
PPP and ABC Target Populations
Mother’s Age at Birth
Father’s Age at age 3.5
Father absent at age 3.5
Neither Parent Employed
Family on Welfare
Mother’s Education (years)
Father’s Education (years)
Household size at age 3.5
No. siblings at age 3.5
Conti, Heckman, Moon, Pinto
PPP
25.5
32.8
47%
41%
50%
9.4
8.6
6.3
4.3
THE HEALTH EFFECTS OF ECIS
ABC
20.3
26.9
69%
55%
43%
10.3
11.0
4.3
1.1
9 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
Curriculum in the ABC and PPP Interventions: Stimulation
PPP
Activities
Teaching Style
Record Keeping
Conti, Heckman, Moon, Pinto
ABC
Curriculum Differences
“Plan, Do, Review”
Learning games
(executive function)
(Sparling & Lewis)
Curriculum Similarities
(1) Individualized teaching: draw from Piaget (active learning)
and Vygotsky (scaffolding)
(2) Progress tracked through logs and notes
THE HEALTH EFFECTS OF ECIS
10 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
I Treated children had breakfast, lunch and afternoon snack at the
center.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
I Treated children had breakfast, lunch and afternoon snack at the
center.
I Food was catered in by kitchens approved by the local health
department, with nutritionist consulted to plan menus.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
I Treated children had breakfast, lunch and afternoon snack at the
center.
I Food was catered in by kitchens approved by the local health
department, with nutritionist consulted to plan menus.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
I Treated children had breakfast, lunch and afternoon snack at the
center.
I Food was catered in by kitchens approved by the local health
department, with nutritionist consulted to plan menus.
The Health Care Component of the ABC Intervention
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
I Treated children had breakfast, lunch and afternoon snack at the
center.
I Food was catered in by kitchens approved by the local health
department, with nutritionist consulted to plan menus.
The Health Care Component of the ABC Intervention
I Treated children also received free basic pediatric care.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
I Treated children had breakfast, lunch and afternoon snack at the
center.
I Food was catered in by kitchens approved by the local health
department, with nutritionist consulted to plan menus.
The Health Care Component of the ABC Intervention
I Treated children also received free basic pediatric care.
I Medical staff on site: 2 pediatricians, a family nurse practitioner and
a licensed practical nurse.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
I Treated children had breakfast, lunch and afternoon snack at the
center.
I Food was catered in by kitchens approved by the local health
department, with nutritionist consulted to plan menus.
The Health Care Component of the ABC Intervention
I Treated children also received free basic pediatric care.
I Medical staff on site: 2 pediatricians, a family nurse practitioner and
a licensed practical nurse.
I Well-child care: assessments at ages 2, 4, 6, 9, 12, 18, 24 months;
then yearly. Complete physical exam + parents counseling.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
I Treated children had breakfast, lunch and afternoon snack at the
center.
I Food was catered in by kitchens approved by the local health
department, with nutritionist consulted to plan menus.
The Health Care Component of the ABC Intervention
I Treated children also received free basic pediatric care.
I Medical staff on site: 2 pediatricians, a family nurse practitioner and
a licensed practical nurse.
I Well-child care: assessments at ages 2, 4, 6, 9, 12, 18, 24 months;
then yearly. Complete physical exam + parents counseling.
I Ill-child care: daily surveillance. In case of illness: doctor visit + lab
tests + treatment until recovery.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Curriculum
The Nutritional Component of the ABC Intervention
I Treated children had breakfast, lunch and afternoon snack at the
center.
I Food was catered in by kitchens approved by the local health
department, with nutritionist consulted to plan menus.
The Health Care Component of the ABC Intervention
I Treated children also received free basic pediatric care.
I Medical staff on site: 2 pediatricians, a family nurse practitioner and
a licensed practical nurse.
I Well-child care: assessments at ages 2, 4, 6, 9, 12, 18, 24 months;
then yearly. Complete physical exam + parents counseling.
I Ill-child care: daily surveillance. In case of illness: doctor visit + lab
tests + treatment until recovery.
I Costs of medicines and referrals to hospitals not included.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
11 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Randomized Controlled Trials
I Standard model of program evaluation:
Yi = Di Yi (1) + (1 − D)Yi (0)
I
I
I
I
Yi : observed outcome of participant i, i = 1, ..., N.
Di : treatment assignment for participant i.
Di = 1 if treatment occurs, Di = 0 otherwise.
(Yi (0), Yi (1)): potential outcomes for participant i.
I Major benefit of a randomized experiment:
(Y (1), Y (0)) ⊥⊥ D|X
I Our goal is to estimate average treatment effects and to test the
null hypothesis of no treatment effect.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
12 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
=⇒ Exact (small sample) permutation-based inference.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
=⇒ Exact (small sample) permutation-based inference.
I Compromised Randomization: non-random re-assignment.
Randomization
Conti, Heckman, Moon, Pinto
Compromises
Block Permutation
THE HEALTH EFFECTS OF ECIS
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
=⇒ Exact (small sample) permutation-based inference.
I Compromised Randomization: non-random re-assignment.
=⇒ Block permutation following the randomization protocol.
Randomization
Conti, Heckman, Moon, Pinto
Compromises
Block Permutation
THE HEALTH EFFECTS OF ECIS
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
=⇒ Exact (small sample) permutation-based inference.
I Compromised Randomization: non-random re-assignment.
=⇒ Block permutation following the randomization protocol.
Randomization
Compromises
Block Permutation
I Cherry Picking: pre-testing and selective reporting of significant
outcomes.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
=⇒ Exact (small sample) permutation-based inference.
I Compromised Randomization: non-random re-assignment.
=⇒ Block permutation following the randomization protocol.
Randomization
Compromises
Block Permutation
I Cherry Picking: pre-testing and selective reporting of significant
outcomes.
=⇒ Multiple hypothesis testing correction: stepdown algorithm developed
by Romano and Wolf [2005]. MHT
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
=⇒ Exact (small sample) permutation-based inference.
I Compromised Randomization: non-random re-assignment.
=⇒ Block permutation following the randomization protocol.
Randomization
Compromises
Block Permutation
I Cherry Picking: pre-testing and selective reporting of significant
outcomes.
=⇒ Multiple hypothesis testing correction: stepdown algorithm developed
by Romano and Wolf [2005]. MHT
I Non-random Attrition: biased sample.
Conti, Heckman, Moon, Pinto
Chart
THE HEALTH EFFECTS OF ECIS
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
=⇒ Exact (small sample) permutation-based inference.
I Compromised Randomization: non-random re-assignment.
=⇒ Block permutation following the randomization protocol.
Randomization
Compromises
Block Permutation
I Cherry Picking: pre-testing and selective reporting of significant
outcomes.
=⇒ Multiple hypothesis testing correction: stepdown algorithm developed
by Romano and Wolf [2005]. MHT
I Non-random Attrition: biased sample.
=⇒ Inverse Probability Weighting (IPW).
Conti, Heckman, Moon, Pinto
Chart
IPW
THE HEALTH EFFECTS OF ECIS
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
=⇒ Exact (small sample) permutation-based inference.
I Compromised Randomization: non-random re-assignment.
=⇒ Block permutation following the randomization protocol.
Randomization
Compromises
Block Permutation
I Cherry Picking: pre-testing and selective reporting of significant
outcomes.
=⇒ Multiple hypothesis testing correction: stepdown algorithm developed
by Romano and Wolf [2005]. MHT
I Non-random Attrition: biased sample.
=⇒ Inverse Probability Weighting (IPW).
Chart
IPW
I Contamination of the Control Group: attendance of alternative
childcare by control families (ABC only). Figure
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Problems and Solutions
I Small Sample: use of classical asymptotic inference questionable.
=⇒ Exact (small sample) permutation-based inference.
I Compromised Randomization: non-random re-assignment.
=⇒ Block permutation following the randomization protocol.
Randomization
Compromises
Block Permutation
I Cherry Picking: pre-testing and selective reporting of significant
outcomes.
=⇒ Multiple hypothesis testing correction: stepdown algorithm developed
by Romano and Wolf [2005]. MHT
I Non-random Attrition: biased sample.
=⇒ Inverse Probability Weighting (IPW).
Chart
IPW
I Contamination of the Control Group: attendance of alternative
childcare by control families (ABC only). Figure
=⇒ Control for selection into daycare among the controls.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
Contamination
13 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Evidence
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
14 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Health and Healthy Behaviors
PPP
I Information on healthy behaviors was collected at ages 27 and 40.
I Self-reported health, height and weight recorded at age 40.
→ On-going age-50 follow-up with biomarkers.
ABC
I Information on healthy behaviors was collected at ages 21 and 30.
I Last data collection (mid 30s) was a biomedical sweep.
I Information was collected from two sources:
I Physical Exam at the doctor’s office.
I Lab tests from venous (non-fasting) blood.
→ First time biomarkers have been collected in a ECI.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
15 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP: Smoking at Ages 27 and 40, Males
Control
Treatment
Blk. IPW P.
Variable
Mean
Mean
p-val
Stepd.
Not a daily smoker at age 27
0.462
0.581
0.080
0.080
Non- or light smoker (≤10/d) at age 27
0.615
0.903
0.004
0.004
No. of cigarettes at age 27
8.744
4.291
0.006
0.007
Smoked <100 cigarettes by age 40
0.444
0.600
0.040
0.040
Not a daily smoker at age 40
0.472
0.633
0.020
0.041
Non- or light smoker (≤10/d) at age 40
0.743
0.929
0.011
0.021
No. of cigarettes at age 40
6.543
3.714
0.036
0.053
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator, and
the median of SES for the 101 eldest siblings only per cohort. Probabilities of IPW are estimated using the following
variables: gender, presence of the father in the home at entry, socio-economic status index (household density, mother and
father education, child IQ at entry (Binet)), and number of siblings a entry. Fifth column presents the stepdown p-values
associated with (5). Blocks are delineated by horizontal lines.
Females
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
16 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP: Other Health Behaviors at Age 40, Males
Control
Treatment
Blk. IPW P.
Variable
Mean
Mean
p-val
Stepd.
Regular physical activity past mo.
0.629
0.567
0.480
0.480
Diet change past 15 yrs.
0.229
0.380
0.018
0.061
Always wears a seat belt
0.618
0.800
0.080
0.080
Never got a traffic ticket
0.265
0.534
0.086
0.097
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator, and
the median of SES for the 101 eldest siblings only per cohort. Probabilities of IPW are estimated using the following
variables: gender, presence of the father in the home at entry, socio-economic status index (household density, mother and
father education, child IQ at entry (Binet)), and number of siblings a entry. Fifth column presents the stepdown p-values
associated with (5). Blocks are delineated by horizontal lines.
Females
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
17 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP: Physical Health at Age 40, Males
Control
Treatment
Blk. IPW P.
Variable
Mean
Mean
p-val
Stepd.
Self-reported weight (kgs)
88.619
91.459
0.672
0.888
Body Mass Index (BMI)
27.426
28.720
0.856
0.856
No overweight
0.543
0.533
0.472
0.946
No obese
0.743
0.667
0.869
0.892
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator, and
the median of SES for the 101 eldest siblings only per cohort. Probabilities of IPW are estimated using the following
variables: gender, presence of the father in the home at entry, socio-economic status index (household density, mother and
father education, child IQ at entry (Binet)), and number of siblings a entry. Fifth column presents the stepdown p-values
associated with (5). Blocks are delineated by horizontal lines.
Females
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
18 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Biomedical Sweep (Mid 30s): Blood Pressure, Males
Variable
Control
Treatment
Mean
Mean
p-val
Blk. IPW P.
Stepd.
Systolic Blood Pressure (mmHg)
143.333
125.789
0.018
0.029
Diastolic Blood Pressure (mmHg)
92.000
78.526
0.024
0.024
Hypertension (S.>140 & D.>90)
0.444
0.105
0.010
0.018
Hypertension (S.>140 or D.>90)
0.556
0.211
0.038
0.038
Notes: (1) The fourth column “Blk. IPW P. p-val” presents the one-sided single hypothesis block permutation p-values
associated with the IPW treatment effect estimate. By block permutation we mean that permutations are done within strata
defined by the pre-program variables used in the randomization protocol: gender, cohort, mother IQ at entry, number of
siblings and high risk index. Probabilities of IPW are estimate using the following variables: prematurity, a dichotomous
indicator for not having an exam for illness or injury in the past two years at age 30, Achenbach DSM
Attention-Deficit/Hyperactivity (AD/H) problems scale at age 30, and Achenbach substance abuse scale. (2) The fifth
column “Blk. IPW P. Stepd.” presents the multiple hypothesis stepdown p-values associated with (2). Blocks are delineated
by horizontal lines.
Females
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
19 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Biomedical Sweep (Mid 30s): Lab Tests, Males
Control
Treatment
Variable
Mean
Mean
p-val
Blk. IPW P.
Stepd.
HDL Cholesterol (mg/dL)
42.000
53.211
0.066
0.110
Dyslipidemia (HDL<40 mg/dL)
0.417
0.106
0.179
0.179
Pre-Diabetes (HbA1C≥5.7%)
0.583
0.473
0.426
0.426
Vit.D Deficiency (<20 ng/mL)
0.750
0.368
0.021
0.021
Notes: (1) The fourth column “Blk. IPW P. p-val” presents the one-sided single hypothesis block permutation p-values
associated with the IPW treatment effect estimate. By block permutation we mean that permutations are done within strata
defined by the pre-program variables used in the randomization protocol: gender, cohort, mother IQ at entry, number of
siblings and high risk index. Probabilities of IPW are estimate using the following variables: prematurity, a dichotomous
indicator for not having an exam for illness or injury in the past two years at age 30, Achenbach DSM
Attention-Deficit/Hyperactivity (AD/H) problems scale at age 30, and Achenbach substance abuse scale. (2) The fifth
column “Blk. IPW P. Stepd.” presents the multiple hypothesis stepdown p-values associated with (2). Blocks are delineated
by horizontal lines. Abbreviations: HDL=High-Density Lipoprotein. HbA1C: Glycosylated Hemoglobin.
Females
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
20 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Biomedical Sweep (Mid 30s): Multiple Risk Factors, Males
Control
Treatment
Blk. IPW P.
Variable
Mean
Mean
p-val
Stepd.
Obesity & Hypertension
0.500
0.111
0.016
0.016
Severe Obesity & Hypertension
0.375
0.000
0.005
0.012
Hypertension & Dyslipidemia
0.333
0.000
0.006
0.012
Metabolic Syndrome (NCEP Def.)
0.250
0.000
0.007
0.014
Framingham Risk Score
7.043
4.889
0.038
0.038
Notes: Abbreviations: NCEP=National Cholesterol Education Program. Definitions: Obesity = BMI≥30; Severe Obesity =
BMI≥35; Hypertension = Systolic bp>140 or Diastolic bp>90; Metabolic Syndrome = (1) central obesity (waist
circumference>102cm or 40in), (2) Dyslipidemia (HDL-C<40 mg/dL), (3) High blood pressure (bp≥130/85 mmHg). The
Framingham Risk Score is calculated according to the equation derived in Wilson et al. [1998]; it measures the risk of
experiencing “total” Coronary Heart Disease (CHD), defined as both stable and unstable angina, myocardial infarction, or
CHD death, within the next 10 years, on the basis of the age, gender, total and HDL cholesterol, systolic and diastolic bp,
diabetes and smoking status.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
21 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC at Ages 21 and 30: Healthy Behaviors, Males
Variable
Control
Treatment
Mean
Mean
Blk. IPW P.
p-val
Stepd.
Never a Regular Smoker at age 30
0.391
0.357
0.571
0.571
Age of Onset of Regular Smoking
16.893
19.722
0.051
0.143
Cigarettes/day past 30d. at age 30
11.167
8.685
0.199
0.344
Exercise 4 or more d/w at age 21
0.391
0.307
0.858
0.858
# of Fruit Servings/day at age 21
0.826
0.846
0.524
0.745
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator,
mother IQ at entry, number of siblings and high risk index. Probabilities of IPW are estimated using a selection of covariates
based on the lowest Akaike Information Criterion (AIC) among models examining all combinations of covariates that present
statistically significant imbalance between attriters and non-attriters. Sixth column presents the stepdown p-values associated
with (5). Blocks are delineated by horizontal lines.
Females
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
22 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Mechanisms
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
23 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
PPP Mechanisms: IQ, Males
105
Treatment
100
95
IQ
90
85
Control
80
75
Treatment
79.2
94.9
95.4
91.5
91.1
88.3
88.4
83.7
Control
77.8
83.1
84.8
85.8
87.7
89.1
89.0
86.0
Entry
4
5
6
7
8
9
Conti, Heckman, Moon, Pinto
Age
THE HEALTH EFFECTS OF ECIS
10
24 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
.8
0
0
.2
.2
.4
.6
density
.6
.4
density
.8
1
1
PPP Mechanisms: Externalizing Behavior, Males
2
2.5
3
3.5
(a) Control
4
4.5
5
2
2.5
®
3
3.5
4
(b) Treatment
4.5
5
®
Source: Heckman, Pinto, and Savelyev (2013).
I Externalizing behavior is the main mediator of the effect of the
treatment on healthy behaviors.
I Experimentally-induced reductions in externalizing behavior explain
between 20% and 55% of the treatment effect on smoking.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
25 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: IQ, Males
120
115
110
105
Treatment
100
95
90
85
Control
Age
80
6 6.5
8
12 15 21
00.25
25 00.5
5 00.75
75 1 11.5
5 2
3 33.5
5 4 44.55 5
65 7
Treatment
94.4 103.6106.6111.2108.8 97.0 101.7102.1102.1101.2101.7106.0 99.5 99.0 97.6 93.8 96.9 87.2
Control
94.9 102.0105.0106.1 95.3 87.6 89.5 93.9 90.9 93.6 93.6 95.2 93.7 92.6 93.5 93.8 93.2 86.6
Treatment + SD 96.90105.9109.3113.7111.298.89103.5103.6103.7102.6103.2109.1101.3101.099.3695.1998.6888.92
Treatment - SD 91.93101.1103.8108.7106.395.1699.80100.5100.399.74100.0102.897.7496.8195.9092.3295.0985.54
Control + SD 97.50104.1108.6108.597.8489.4691.8296.1693.1795.8096.2599.0396.2895.3096.2496.1295.8388.37
Control - SD 92.2899.96101.4103.792.7385.8287.2791.6288.5391.3691.0291.2991.2089.8990.7091.4790.5584.77
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
26 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
0
.1
.2
.3
.4
.5
ABC Mechanisms: Confidence at 24mo., Males
1
2
Treated, M
Conti, Heckman, Moon, Pinto
3
Control, M
4
5
Treated, F
THE HEALTH EFFECTS OF ECIS
Control, F
27 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
0
.2
.4
.6
ABC Mechanisms: Confidence at 36mo., Males
1
2
Treated, M
Conti, Heckman, Moon, Pinto
3
Control, M
4
5
Treated, F
THE HEALTH EFFECTS OF ECIS
6
Control, F
28 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
0
.2
.4
.6
.8
ABC Mechanisms: Confidence at 48mo., Males
2
Treated, M
Conti, Heckman, Moon, Pinto
3
Control, M
4
5
Treated, F
THE HEALTH EFFECTS OF ECIS
6
Control, F
29 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
0
.2
.4
.6
ABC Mechanisms: Confidence at 60mo., Males
2
Treated, M
Conti, Heckman, Moon, Pinto
3
Control, M
4
5
Treated, F
THE HEALTH EFFECTS OF ECIS
6
Control, F
30 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Control
Treatment
Abecedarian Intervention
HOME Score Items
Mean
Mean
Child regular preventive health care at 6 mo.
0.826
Child regular preventive health care at 18 mo.
Child regular preventive health care at 30 mo.
Conclusions
Blk. IPW P.
p-val
Stepd.
1.000
0.023
0.088
0.857
1.000
0.008
0.036
0.810
1.000
0.086
0.402
Delay of food gratification at 42 mo.
0.619
0.760
0.175
0.175
Delay of food gratification at 60 mo.
0.476
0.826
0.017
0.017
Males
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator,
mother IQ at entry, number of siblings and high risk index. Probabilities of IPW are estimated using a selection of covariates
based on the lowest Akaike Information Criterion (AIC) among models examining all combinations of covariates that present
statistically significant imbalance between attriters and non-attriters. Sixth column presents the stepdown p-values associated
with (5). Blocks are delineated by horizontal lines.
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.1
Density
.2
.3
Birth
5
10
15
BMI
Treated
20
25
Control
®
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
.05
.1
Density
.15
.2
.25
.3
3 Months
12
14
16
18
20
22
BMI
Treated
Control
®
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.1
Density
.2
.3
6 Months
12
14
16
18
20
22
BMI
Treated
Control
®
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.2
Density
.4
.6
9 Months
12
14
16
18
20
22
BMI
Treated
Control
®
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.1
Density
.2
.3
.4
12 Months
12
14
16
18
20
22
BMI
Treated
Control
®
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.1
Density
.2
.3
.4
.5
18 Months
12
14
16
18
20
22
BMI
Treated
Control
®
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.2
Density
.4
.6
24 Months
12
14
16
18
20
22
BMI
Treated
Control
®
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.2
Density
.4
.6
36 Months
12
14
16
18
20
22
BMI
Treated
Control
®
Conti, Heckman, Moon, Pinto
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.1
Density
.2
.3
.4
48 Months
12
14
16
18
20
22
BMI
Treated
Control
®
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.1
Density
.2
.3
.4
60 Months
12
14
16
18
20
22
BMI
Treated
Conti, Heckman, Moon, Pinto
Control
THE HEALTH EFFECTS OF ECIS
®
41 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
0
.1
Density
.2
.3
96 Months
12
14
16
18
BMI
Treated
20
22
24
Control
®
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
-1
-.5
z-Score
0
.5
1
1.5
ABC Mechanisms: BMI, Males
0
3
6
9
12
18
24
Age(months)
Treatment
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
36
48
Control
43 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
-.5
0
z-Score
.5
1
ABC Mechanisms: BMI, Males
24
36
48
60
Age(months)
Treatment
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96
Control
44 / 56
Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
-1
-.5
z Score
0
.5
1
ABC Mechanisms: Height, Males
0 3 6 9 12 18 24
36
48
60
Age (months)
Treatment
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96
Control
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
-1
-.5
z Score
0
.5
1
ABC Mechanisms: Weight, Males
0 3 6 9 12 18 24
36
48
60
Age (months)
Treatment
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96
Control
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
-1
-.5
z-Score
0
.5
1
ABC Mechanisms: BMI, Males
0
3
6
9
12
18
24
Age(months)
Not Obese Mid-30s
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36
48
Obese Mid-30s
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
-1
-.5
z-Score
0
.5
1
ABC Mechanisms: BMI, Males
24
36
48
60
Age(months)
Not Obese Mid-30s
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96
Obese Mid-30s
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: Obesity, Males
Control
Treatment
Condit.
Variable
Mean
Mean
TE
p-val
Blk. IPW P.
Stepd.
At Risk Overweight at 3 months
0.227
0.037
0.206
0.026
0.121
At Risk Overweight at 6 months
0.250
0.080
0.205
0.074
0.182
At Risk Overweight at 9 months
0.412
0.000
0.446
0.004
0.023
At Risk Overweight at 12 months
0.429
0.000
0.408
0.001
0.009
At Risk Overweight at 18 months
0.389
0.000
0.385
0.000
0.004
At Risk Overweight at 24 months
0.333
0.000
0.343
0.001
0.011
At Risk Overweight at 36 months
0.158
0.080
0.094
0.194
0.194
At Risk Overweight at 48 months
0.300
0.167
0.133
0.150
0.235
At Risk Overweight at 60 months
0.300
0.125
0.187
0.058
0.179
At Risk Overweight at 96 months
0.421
0.120
0.286
0.030
0.117
Weight-for-Length ∆ 0-24m (CDC)
0.858
-0.105
1.176
0.058
0.058
Weight-for-Length ∆ 0-24m (WHO)
1.265
0.166
1.397
0.049
0.057
Notes: We use weight-for-length ≥ 85th percentile for being “at-risk overweight” under 24 months, and BMI-for-age ≥ 85th
percentile for being overweight for 24 months and older.
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
ABC Mechanisms: BMI, Males
I BMI around one year of age is the main mediator of the effect of the
treatment on hypertension and obesity in the mid-30s.
I Experimentally-induced reductions in BMI in the treatment group
explain between 50% and 70% of the treatment effect on
hypertension and obesity.
I Preliminary results show that the occurrence of hospitalizations in
the last 3 years at age 15 explain a large share of the effect of the
treatment on multiple risk factors.
Conti, Heckman, Moon, Pinto
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Parental Responses
Conti, Heckman, Moon, Pinto
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
10
20
Proportion
30
40
50
PPP Parental Responses: Beliefs, Males
−.015
−.01
−.005
0
.005
Belief in Importance of Parenting
Control
Conti, Heckman, Moon, Pinto
.01
.015
Treatment
THE HEALTH EFFECTS OF ECIS
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
.0004
.0006
Density
.0008
.001
.0012
ABC Parental Responses: Attachment, Males
0
200
400
600
Duration (Seconds)
Treated
Conti, Heckman, Moon, Pinto
800
1000
Control
THE HEALTH EFFECTS OF ECIS
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Conclusions
I Analyzed the health effects of two flagships ECIs: the Perry
Preschool Project and the Abecedarian interventions.
I PPP: males in the treated group have significantly lower prevalence
of unhealthy behaviors (esp. smoking) in adulthood.
I ABC: males in the treated group have significantly lower prevalence
of cardiovascular and metabolic risk factors in their mid 30s.
I Examined the mechanisms through which these interventions
operated to promote health and healthy behaviors.
I PPP: significantly lower prevalence of problem behavior in childhood.
I ABC: significantly lower prevalence of overweight in childhood.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Conclusions
I Analyzed the health effects of two flagships ECIs: the Perry
Preschool Project and the Abecedarian interventions.
I PPP: males in the treated group have significantly lower prevalence
of unhealthy behaviors (esp. smoking) in adulthood.
I ABC: males in the treated group have significantly lower prevalence
of cardiovascular and metabolic risk factors in their mid 30s.
I Examined the mechanisms through which these interventions
operated to promote health and healthy behaviors.
I PPP: significantly lower prevalence of problem behavior in childhood.
I ABC: significantly lower prevalence of overweight in childhood.
I Investigated whether these interventions complement, or substitute
for, parental investments.
I PPP: increased beliefs in the importance of parenting.
I ABC: improved attachment between mother and children.
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
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Intro
PPP and ABC
Method
Evidence
Mechanisms
Conclusions
Conclusions
Our results show the potential of early life interventions to prevent
disease and promote health.
Conti, Heckman, Moon, Pinto
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Appendix
Appendix
Conti, Heckman, Moon, Pinto
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Appendix
Abecedarian Design
Figure
1 : Design of Abecedarian Study
PERSISTENT EFFECTS OF CHILDHOOD EDUCATION
Figure 2. Design of Abecedarian Project.
Source: Ramey et al. (2000)
within both the preschool treatment and control
groups. One member of each consecutive pair within
grounds in primary education, and successful experience in working with at-risk children and families.
back
Known as Home–School Resource Teachers (HSTs),
each group was then assigned randomly to the AbeceConti, Heckman, Moon, Pinto
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Appendix
Table 1 : Quality and Service Provision in the ABC and PPP Interventions
PPP
Training
Degree
Qualifications
Salary
Child-Teacher
Ratio
Home Visits
Parent Involvement
ABC
Educator’s Background
Regular Training
Periodic on-site training
Bachelors
Graduate degree and paraprofessionals
Certificate in Elementary
Extensive Experience
+ Special Education
Similar to public teacher
Based on public school pay scale
+10% for participation
Classroom
5:1 to 6:1
3:1 (Nursery); 4:1 (Toddlers);
6:1 (School)
Services Offered
Biweekly teacher visits
Social work visits as needed,
1.5hrs, 1:1 tutoring
for legal help, family planning.
Monthly group meetings
Newsletter sent home
back
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Appendix
Table 2 : Randomization in the ABC and PPP Interventions
PPP
ABC
Randomization Protocol
For each of the 5 waves:
For all eligible 122 children by cohort:
(a) Rank by (1) IQ at entry (2) gender and
(a) Match in pairs by HRI rating,
mother’s IQ, gender and number of
(3) SES of the eldest sibling
(b) Assign even and odds by rank and group
siblings (precise pairs unknown)
in pairs
(b)Toss coin for T-C status
(c) Toss coin for T-C status
Compromises of the Randomization Protocol
(1) Initial assignments switched to
(1) 8 declined participation after learning
balance gender and socio-economic status
assignment (7 T, 1 C) (non-compliance)
(2) After assignment, working moms switched
(2) 2 controls assigned to treatment
to control group since could not participate
at the request of local authorities
in home visits and transportation issues
+ 1 control diagnosed with retardation
associated with seizures was dropped
(non-random reassignment)
back
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Appendix
Small Sample with Compromised Randomization
Problem: Small Sample with Compromised Randomization
I Induces a correlation between treatment status and
unobserved/observed variables.
I Counterfactual outcomes are different from conditional outcomes:
d
(Y (0), Y (1)) 6= (Y |D = 0), (Y |D = 1)
I Casts doubts on standard estimations that ignore compromises.
I Needs a conditional independence assumption:
(Y (1), Y (0)) ⊥⊥ D | X
I where X are the variables used in the randomization protocol:
I PPP: cohort, gender, child IQ, SES, maternal employment.
I ABC: cohort, gender, maternal IQ, High Risk Index, number of
siblings.
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Appendix
Small Sample with Compromised Randomization
Solution: Permutation Test tailored to the randomization protocol
I Use two assumptions:
I Conditional exchangeability property: the distribution of D is invariant under valid
permutation (b/c of randomization).
I Null of no treatment effect: vector of Y independent of the vector of D (to
generate permutation test).
Theorem
Randomization Hypothesis: the joint distribution of outcomes Y and treatment assignments
D are invariant under permutations GX of treatment assignments within strata formed by
d
values of covariates X , that is: (Y , D) = (Y , gD) ∀ g ∈ GX
=⇒ a statistic based on assignments D and outcomes Y is distribution-invariant under
permutations g ∈ GX .
I Permutation test: compare a test statistic computed on the original (unpermuted) data
with a distribution of test statistics computed on resamplings of that data according to
permutations in GX .
I The p-value, is computed as the fraction of resampled data which yields a test statistic
greater than that yielded by the original data.
back
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Appendix
Cherry Picking
Solutions: Multiple Hypothesis Testing (MHT)
Type-I Error in Multiple-Hypothesis Testing
I Goal: control for familywise error rate (FWER) at a given level α:
FWER = P {reject any true null hypothesis in a joint test of a set of hypotheses} ≤ α
We perform multiple-hypothesis testing using the Stepdown Algorithm:
I Starts by targeting the most significant test statistic.
I Decides if it is statistically significant or not.
I “Steps down” to smaller, less significant test statistics.
I Less Conservative than traditional Bonferroni and Holm procedure
by incorporating the dependence structure of the test statistics.
I Generates as many adjusted p-values as there are hypotheses.
I Romano and Wolf [2005] show that stepdown provides strong
FWER control (controls FWER regardless of which subset of the
null hypotheses are actually true).
back
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Appendix
Attrition
Problem: Attrition
I Outcome Y not observed for some participants.
I Y (d) ⊥⊥ D|X holds, but Y (d) ⊥⊥ D|X , A = 1 may not hold.
I There could be differential attrition: D ⊥⊥ A|X may not hold.
Solution: Inverse Probability Weighting
I Key idea: retrieve statistics for the full outcome distribution through reweighing
non-missing observations according to their likelihood of compliance.
I IPW relies on a matching on observables assumption: Y (d) ⊥⊥ A|(D, X , Z )
I Z are pre-program variables other than X, and variables in the previous period (Robins et al. [1995],
Fitzgerald et al. [1998])
I Applying Bayes’ Theorem we get the standard IPW formula for ATE:
Y 1[A=1,D=1]
Y 1[A=1,D=0]
E(Y (1) − Y (0)) = E( Pr(A=1|D=1,X ,Z ) Pr(D=1|X ,Z ) ) −( Pr(A=1|D=0,X ,Z ) Pr(D=0|X ,Z ) )
I We use a logit to estimate the probability of participation, separately for each
gender.
I The selection of covariates is based on the lowest AIC among models examining
all combinations of covariates imbalanced between attriters and non-attriters.
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Appendix
Attrition
d=
ATE
N
X
Yi · 1 [Di = 1] · 1 [Ai = 1] · ωi,1
N1
i=1
where ωi,d =
1
p̂i,d
1
Nd
−
N
X
Yi · 1 [Di = 0] · 1 [Ai = 1] · ωi,0
i=1
N
X
1 [Di = d] · 1 [Ai = 1]
p̂j,d
j=1
and pi,d = Pr(A = 1|D = d, Xi , Zi ) Pr(D = d|Xi , Zi )
N0
(1)
d ∈ {0, 1}
d ∈ {0, 1}
N
where Nd =
X
1 [Di = d] · 1 [Ai = 1];
d ∈ {0, 1}
i=1
back
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Appendix
Attrition
Attrition in the Abecedarian Intervention
Wave
Baseline
3m
6m
12m
18m
24m
36m
48m
60m
8y
21y
30y
35y (lab)
35y (PE)
Treated M
Foll.
Attr.
29
28
1
25
4
27
2
26
3
27
2
25
4
24
5
26
3
26
3
28
1
27
2
20
7
19
8
Treated F
Foll.
Attr.
28
23
5
24
4
24
4
22
6
23
5
21
7
22
6
23
5
23
5
25
3
25
3
18
7
18
7
Control M
Foll.
Attr.
23
22
1
22
1
21
2
20
3
15
8
19
4
20
3
21
2
19
4
23
0
21
2
12
9
9
11
Control F
Foll.
Attr.
31
26
5
27
4
25
6
27
4
17
14
23
8
26
5
25
6
24
7
28
3
28
3
22
6
22
6
back
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Appendix
Contamination of the Control Group
Problem: Contamination of the Control Group
0
.1
Fraction
.2
.3
.4
Figure 2 : ABC, Out-of-Home Care Attendance of the Control group
0
20
40
Months in Day−Care, Countrol Group
60
Notes: Total number of months of out-of-home day-care services experienced by the
control group over ages 0–5 years old.
back
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Appendix
Contamination of the Control Group
Solution: Linear Model Based on Matching on Observables
I Two issues:
I selection of out-of-home care
I small sample
I Two solutions:
I conditional independence: Y (0, t) ⊥⊥ T | (X , W ) ∀ t ∈ supp(T )
Y (0, t) is the outcome Y when the out-of-home care choice T is set
at t for D = 0
W is a set of pre-program variables different from X
t ∈ [0, 60] is the length of daycare
I linearity: Yi = τ + βW Wi + βX Xi + βT Ti + i for Di = 0
I So the counterfactual outcome now is Ŷi (0, 0) = τ̂ + β̂W Wi + β̂X Xi .
back
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Appendix
Contamination of the Control Group
PPP: Smoking at Ages 27 and 40, Females
Control
Treatment
Blk. IPW P.
Variable
Mean
Mean
p-val
Stepd.
Not a daily smoker at age 27
0.409
0.520
0.107
0.283
Non- or light smoker (≤10/d) at age 27
0.818
0.760
0.661
0.661
No. of cigarettes at age 27
7.682
7.600
0.300
0.487
Smoked <100 cigarettes by age 40
0.409
0.458
0.142
0.503
Not a daily smoker at age 40
0.409
0.522
0.127
0.356
Non- or light smoker (≤10/d) at age 40
0.773
0.870
0.385
0.442
No. of cigarettes at age 40
6.818
5.869
0.483
0.483
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator, and
the median of SES for the 101 eldest siblings only per cohort. Probabilities of IPW are estimated using the following
variables: gender, presence of the father in the home at entry, socio-economic status index (household density, mother and
father education, child IQ at entry (Binet)), and number of siblings a entry. Fifth column presents the stepdown p-values
associated with (5). Blocks are delineated by horizontal lines.
back
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Appendix
Contamination of the Control Group
PPP: Other Health Behaviors at Age 40, Females
Control
Treatment
Blk. IPW P.
Variable
Mean
Mean
p-val
Stepd.
Regular physical activity past mo.
0.091
0.375
0.002
0.038
Diet change past 15 yrs.
0.227
0.375
0.287
0.287
Always wears a seat belt
0.818
0.750
0.813
0.813
Never got a traffic ticket
0.409
0.417
0.661
0.856
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator, and
the median of SES for the 101 eldest siblings only per cohort. Probabilities of IPW are estimated using the following
variables: gender, presence of the father in the home at entry, socio-economic status index (household density, mother and
father education, child IQ at entry (Binet)), and number of siblings a entry. Fifth column presents the stepdown p-values
associated with (5). Blocks are delineated by horizontal lines.
back
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Appendix
Contamination of the Control Group
PPP: Physical Health at Age 40, Females
Control
Treatment
Blk. IPW P.
Variable
Mean
Mean
p-val
Stepd.
Self-reported weight (kgs)
72.665
68.668
0.259
0.766
Body Mass Index (BMI)
26.829
26.283
0.886
0.962
No overweight
0.550
0.556
0.365
0.960
No obese
0.800
0.833
0.884
0.884
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator, and
the median of SES for the 101 eldest siblings only per cohort. Probabilities of IPW are estimated using the following
variables: gender, presence of the father in the home at entry, socio-economic status index (household density, mother and
father education, child IQ at entry (Binet)), and number of siblings a entry. Fifth column presents the stepdown p-values
associated with (5). Blocks are delineated by horizontal lines.
back
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
3/8
Appendix
Contamination of the Control Group
ABC Biomedical Sweep (Mid 30s): Blood Pressure, Females
Variable
Control
Treatment
Condit.
Mean
Mean
TE
p-val
Blk. IPW P.
Stepd.
Systolic Blood Pressure (mmHg)
135.636
129.666
2.185
0.300
0.380
Diastolic Blood Pressure (mmHg)
89.227
85.333
1.204
0.446
0.446
Pre-Hypertension (S.>120 & D.>80)
0.727
0.500
0.101
0.222
0.222
Pre-Hypertension (S.>120 or D.>80)
0.909
0.667
0.244
0.042
0.069
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator,
mother IQ at entry, number of siblings and high risk index. Probabilities of IPW are estimated using a selection of covariates
based on the lowest Akaike Information Criterion (AIC) among models examining all combinations of covariates that present
statistically significant imbalance between attriters and non-attriters. Sixth column presents the stepdown p-values associated
with (5). Blocks are delineated by horizontal lines.
back
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
4/8
Appendix
Contamination of the Control Group
ABC Biomedical Sweep (Mid 30s): Obesity, Females
Control
Treatment
Condit.
Blk. IPW P.
Variable
Mean
Mean
TE
p-val
Stepd.
Overweight (BMI ≥25)
0.955
0.889
0.054
0.482
0.690
Obese (BMI ≥30)
0.727
0.666
-0.112
0.790
0.790
Severely Obese (BMI ≥35)
0.364
0.223
0.143
0.354
0.653
Waist-Hip Ratio (WHR)
0.933
0.876
0.053
0.063
0.101
Abdominal Obesity (WHR≥0.85)
0.762
0.563
0.198
0.080
0.080
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator,
mother IQ at entry, number of siblings and high risk index. Probabilities of IPW are estimated using a selection of covariates
based on the lowest Akaike Information Criterion (AIC) among models examining all combinations of covariates that present
statistically significant imbalance between attriters and non-attriters. Sixth column presents the stepdown p-values associated
with (5). Blocks are delineated by horizontal lines.
back
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
5/8
Appendix
Contamination of the Control Group
ABC at Ages 21 and 30: Healthy Behaviors, Females
Variable
Control
Treatment
Condit.
Mean
Mean
TE
p-val
Blk. IPW P.
Stepd.
Never a Regular Smoker at age 30
0.357
0.600
0.221
0.071
0.195
Age of Onset of Regular Smoking
17.861
17.050
-1.544
0.848
0.848
Cigarettes/day past 30d. at age 30
10.294
10.450
-0.939
0.567
0.807
Exercise 4 or more d/w at age 21
0.071
0.320
0.287
0.004
0.008
# of Fruit Servings/day at age 21
0.286
0.800
0.518
0.004
0.005
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator,
mother IQ at entry, number of siblings and high risk index. Probabilities of IPW are estimated using a selection of covariates
based on the lowest Akaike Information Criterion (AIC) among models examining all combinations of covariates that present
statistically significant imbalance between attriters and non-attriters. Sixth column presents the stepdown p-values associated
with (5). Blocks are delineated by horizontal lines.
back
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
6/8
Appendix
Contamination of the Control Group
ABC Age 30: Health Care, Males
Control
Treatment
Condit.
Variable
Mean
Mean
TE
p-val
Blk. IPW P.
Stepd.
Health Insurance Coverage
0.476
0.704
0.226
0.039
0.039
Buys Health Insurance
0.333
0.650
0.248
0.035
0.080
Hospital or Doctor Care When Sick
0.524
0.815
0.265
0.037
0.068
Notes: Fourth column presents the one-sided single hypothesis constrained permutation p-value based on the IPW t-statistic
associated with the difference in means between treatment groups. By constrained permutation we mean that permutations
are done within strata defined by the pre-program variables used in the randomization protocol: gender, cohort indicator,
mother IQ at entry, number of siblings and high risk index. Probabilities of IPW are estimated using a selection of covariates
based on the lowest Akaike Information Criterion (AIC) among models examining all combinations of covariates that present
statistically significant imbalance between attriters and non-attriters. Sixth column presents the stepdown p-values associated
with (5). Blocks are delineated by horizontal lines.
back
Conti, Heckman, Moon, Pinto
THE HEALTH EFFECTS OF ECIS
7/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small double RCT
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I What: small double RCT
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I What: small double RCT
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I School-age (age 5–8):
n=95: 49 T, 47 C
Child-Teacher Ratio: 6:1
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I What: small double RCT
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I School-age (age 5–8):
n=95: 49 T, 47 C
Child-Teacher Ratio: 6:1
I Where: Chapel Hill, North Carolina
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I What: small double RCT
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I School-age (age 5–8):
n=95: 49 T, 47 C
Child-Teacher Ratio: 6:1
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I What: small double RCT
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I School-age (age 5–8):
n=95: 49 T, 47 C
Child-Teacher Ratio: 6:1
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I Who: 98% African-American children
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I What: small double RCT
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I School-age (age 5–8):
n=95: 49 T, 47 C
Child-Teacher Ratio: 6:1
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I Who: 98% African-American children
I How: 50 w/y, 40 h/w (8 h/d)
social work visits (day-care treatment)
home visits (school-age treatment)
newsletter sent to parents
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
I What: small double RCT
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I School-age (age 5–8):
n=95: 49 T, 47 C
Child-Teacher Ratio: 6:1
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I Who: 98% African-American children
I How: 50 w/y, 40 h/w (8 h/d)
social work visits (day-care treatment)
home visits (school-age treatment)
newsletter sent to parents
I How long: 5y (ages 0-5), 3y (ages 5-8)
Design
More
THE HEALTH EFFECTS OF ECIS
8/8
Appendix
Contamination of the Control Group
ABC
PPP
I What: small RCT
I Day-care (age 3–4):
n=123: 58 T, 65 C, 5 cohorts
Child-Teacher Ratio: 5:1 to 6:1
I Where: Ypsilanti, Michigan
I When: 1963–1967, children born
1958–1962
I Who: all African-American children
I How: 30 w/y, 12.5 h/w (2.5 h/d)
3 h/w (1.5 h/d) teacher home visits
1/mo parents group meetings
I How long: 2y (ages 3-4) for Cohorts
1-4; 1y for Cohort 0
I How much: $9,604.30 (2010$) per
child/year
Conti, Heckman, Moon, Pinto
I What: small double RCT
I Day-care (age 0–5):
n=111: 57 T, 54 C, 4 cohorts
Child-Teacher Ratio: 3:1
(Nursery); 4:1 (Toddlers)
I School-age (age 5–8):
n=95: 49 T, 47 C
Child-Teacher Ratio: 6:1
I Where: Chapel Hill, North Carolina
I When: children born 1972–1977
I Who: 98% African-American children
I How: 50 w/y, 40 h/w (8 h/d)
social work visits (day-care treatment)
home visits (school-age treatment)
newsletter sent to parents
I How long: 5y (ages 0-5), 3y (ages 5-8)
I How much: $15,388 (2010$) per
child/year
Design
More
THE HEALTH EFFECTS OF ECIS
8/8