the young lives study: presentation for longitudinal studies and its application in social policy...
TRANSCRIPT
The Young Lives Study
Alan Sánchez (GRADE)
Presentation for Longitudinal Studies and its Application in Social Policy Workshop
The Young Lives Study: 4 countries, 2 cohorts, 15 years
• The Young Lives Study is an international study on childhood poverty, funded (mainly) by DFID and implemented by Oxford University (Dept. of Int. Dev.) and partners in the study countries.
• Data is collected in Ethiopia, India (Andrah Pradesh and Telangana), Peru and Vietnam. – 3 middle-income countries, 1 low-income country.
• Institutions involved in the study countries: GRADE and IIN in Peru; EDRI in Ethiopia; CESS in India; CAF-VASS in Vietnam.
The Young Lives Study: 4 countries, 2 cohorts, 15 years
• In each country, two cohorts are tracked (12,000 in total): – A cohort of 2,000 children born in 2001-2002 (younger cohort). – A parallel cohort of 1,000 children born in 1994-1995 (older cohort).
• Data collection started in 2002. The fifth survey wave will take place in 2016.
• A parallel qualitative study started in 2007, with 50 children (25 in each cohort) tracked in each country. Four waves have been completed.
R1 R2 R3 R4
Older cohort
6-18 months
4-5 y. 7-8 y. 11-12 y.
R1 R2 R3 R4 7-8 y. 11-12 y. 14-15 y. 18-19 y.
Younger cohort
R5 14-15 y.
R5 21-22 y.
2002 2006 2009 2013 2016
A glance of the data collected
R1 R2 R3 R4
Older cohort
6-18 months
4-5 y. 7-8 y. 11-12 y.
R1 R2 R3 R4 7-8 y. 11-12 y. 14-15 y. 18-19 y.
Younger cohort
R5 14-15 y.
R5 21-22 y.
2002 2006 2009 2013 2016
A glance of the data collected
R1 R2 R3 R4
Older cohort
6-18 months
4-5 y. 7-8 y. 11-12 y.
R1 R2 R3 R4 7-8 y. 11-12 y. 14-15 y. 18-19 y.
Younger cohort
R5 14-15 y.
R5 21-22 y.
Since 2007: Qualitative study
Since 2007: Qualitative study
2002 2006 2009 2013 2016
A glance of the data collected
A glance of the data collected
1. Household Questionnaire
2. Individual Questionnaire for Index Children
3. Self-Administered Questionnaire
4. Community and Mini Community Questionnaire
5. Anthropometrics (for index children and mothers)
6. Learning tests
1. PPVT, Math, Reading Comprehension
2. Executive Functions
7. Selected outcomes for younger siblings (Younger Cohort)
Sampling approach • Principles:
– Oversample poor areas (“pro-poor” samples).
– Samples should reflect countries diversity (ethnical, geographical, social).
– Sampling design should allow to study the context in which children live.
• A two-stage sampling procedure was chosen: – In each country, 20 sites were sampled (non-randomly, except in Peru)
– 100 children randomly selected in each site (50 children in older cohort).
• In Peru, 20 districts were randomly sampled from the universe of districts excluding the wealthiest 5%.
9
Wealth Index Distribution in Peru: YL Peru and DHS Peru
Samples not nationally representative, but informative of living standard conditions accross most of the
“wealth distribution” in each country.
YOUNGER COHORT
OLDER COHORT
Round 1
Round 3
YOUNGER COHORT
OLDER COHORT
Younger Cohort Older Cohort
Deaths 1.1% 0.8%
Refusals 4.0% 6.3%
Not located 1.0% 2.2%
Move abroad 1.2% 1.7%
Interviewed in 2013 93.7% 89.7%
Attrition 6.3% 10.3%
Attrition in Peru: Round 1 (2002) vs Round 4 (2013)
Younger Cohort Older Cohort
Deaths 1.1% 0.8%
Refusals 4.0% 6.3%
Not located 1.0% 2.2%
Move abroad 1.2% 1.7%
Interviewed in 2013 93.7% 89.7%
Attrition 6.3% 10.3%
Attrition in Peru: Round 1 (2002) vs Round 4 (2013)
46.7
62.2
38.4
35.2
21.3 22.6
13.212.5
0
10
20
30
40
50
60
70
1-2 años 4-5 años 7-8 años 11-12 años 14-15 años 18-19 años
Cohorte menor (rural) Cohorte menor (urbano)
% below – 2 S.D. (HEIGHT-FOR-AGE)
Data analysis example: comparing height-for-age (% below -2 S.D.) across cohorts
46.7
62.2
38.4
35.2
21.3 22.6
13.212.5
57.9
0
10
20
30
40
50
60
70
1-2 años 4-5 años 7-8 años 11-12 años 14-15 años 18-19 años
Cohorte mayor (rural)
% below – 2 S.D. (HEIGHT-FOR-AGE)
46.7
62.2
38.4
35.2
21.3 22.6
13.212.5
57.9
0
10
20
30
40
50
60
70
1-2 años 4-5 años 7-8 años 11-12 años 14-15 años 18-19 años
Cohorte mayor (rural) 22.7 p.p.
% below – 2 S.D. (HEIGHT-FOR-AGE)
46.7
62.2
38.4
35.2
21.3 22.6
13.212.5
29.8
0
10
20
30
40
50
60
70
1-2 años 4-5 años 7-8 años 11-12 años 14-15 años 18-19 años
Cohorte mayor (urbano)
% below – 2 S.D. (HEIGHT-FOR-AGE)
46.7
62.2
38.4
35.2
21.3 22.6
13.212.5
29.8
0
10
20
30
40
50
60
70
1-2 años 4-5 años 7-8 años 11-12 años 14-15 años 18-19 años
Cohorte mayor (urbano)
17.3 p.p.
% below – 2 S.D. (HEIGHT-FOR-AGE)
Key opportunities
1. Rich longitudinal data collected over 12 years.
2. Learning across countries (some examples: design of learning. test scores, validation documents; annual meetings).
3. Capacity building (especially for Young Researchers; North-South, South-North, South-South).
4. Building of international networks (NIH-Gates example).
Key challenges • Cohort mantainance – strategies:
– Tracking between rounds.
– Reciprocity
• Family picture; small gift for the index child.
• Information sheet about public services available.
• Information to families about height/weight/vocabulary test of the index child .
• Information about study findings shared with local authorities.
– Retention of fieldworkers over time (as much as possible)
– Collect contact information of family members, relatives and neighbours.
Key challenges
• Other logistical aspects:
– Validation of instruments across countries; translation of questionnaires.
– Attrition in the older cohort.
– Increasing survey costs (due to migration).
• Research aspects:
– Request to access confidential data.
– Collaboration accross study countries.
