Longitudinal Research with the children of the Millennium. Highlights and overall key messages

Poverty and inequality
Early childhood development
Research Report


This brief, produced in partnership with UNICEF Ethiopia, draws on 15 years longitudinal research by Young Lives Ethiopia and the Country Report, highlighting the context in which this research was conducted, cross-country findings, and key implications for policy and practice. The full report is available on the Young Lives Ethiopia website. The research brief is one of the five briefs produced under the joint work of Young Lives and UNICEF.  The remaining four briefs, to be published in coming months, are on early marriage, early childhood development and education, violence and adolescence. 

Tracing the consequences of child poverty - reflections from co-author Andrew Dawes on findings from 15 years of research

After several years in the making, ‘Tracing’, as we authors have come to call the volume, is published. What a journey it has been! Tracing draws on over 800 research papers, fact sheets, country reports and other outputs generated since the inception of the Young Lives study in 2001.

When asked by Jo Boyden to assist in this venture, I asked myself how on earth do we extract and synthesise Young Lives findings gathered over 16 years, to produce a concise account of the impact of poverty on children’s lives in four countries, that is at once scientifically rigorous, of interest to researchers in diverse fields, and perhaps most importantly, provides evidence that assists policy makers in their efforts to improve children’s lives?

Much of the answer lies in the deep knowledge of the project held by authors Jo Boyden and Paul Dornan who together with the Young Lives team, knew where to drill down to construct a powerful story of what matters in children’s lives both in relation to compounding disadvantage or supporting positive growth and development. 

Both the Young Lives International Advisory Board and the ‘Tracing’ Advisory Group, or TAG as we called it, challenged us to go beyond the ‘business as usual’ child poverty story and mine for nuggets that would shift the policy and intervention discourse. 

Taking this advice, we were able to demonstrate that while particular aspects of disadvantage are essential to address (e.g. under-nutrition; poor quality schooling), it is intersecting inequalities and disadvantages that are particularly powerful in undermining human development from before infancy through adolescence and youth. These include the poorest and rural children who are also members of marginalised groups (e.g. ethnic, caste or language), with less educated parents. Policies therefore need to pay particular attention to children who face these intersecting challenges.

A further example of the impact of intersecting disadvantage is evident from Latent Growth Modelling (LGM) an approach I discuss in an article here with Colin Tredoux. In Tracing, LGM traces the consequences of disadvantage in early and middle childhood and adolescence for the development of maths and language skills (vocabulary and reading comprehension). Modelling shows how children from poorer backgrounds with less educated caregivers either don't attend a preschool or attend one that is likely poor quality. That missed opportunity is associated with weaker quantitative and language skills by age five enduring through childhood.

A much-overlooked consequence of poverty is its potential impact on the psychological well-being of primary caregivers. LGM shows how the mental state of caregivers affected by poverty is related to child growth in the early years; those more negatively affected are likely to have children with stunted growth. That in turn compromises cognitive skills in both early and middle childhood. New challenges emerge in early adolescence for children who have to work to assist poor families - they have less time for schooling and studying. So a poor start compounded by other demands in later years contributes to poor skills development by adolescence. This in turn is likely to compromise education outcomes and ultimately the chance to enter further education, training and decent work. 

Patterns such as this are evident throughout the Young Lives data and are what we refer to as Developmental Cascades, a term drawn from the work of Ann Masten and Dante Cicchetti  As LGM shows, cascades occur both within and across stages of childhood development and build upon one another so that their effects accumulate to shape developmental outcomes over time.

For example, the study measured children’s height for their age at each Round. This enabled us to discover a very important nugget; evidence of both growth recovery and faltering during middle childhood. A proportion of children whose growth was stunted in early childhood showed normal growth in middle childhood, while some who had shown normal early growth, were stunted later. Thus early growth status is not necessarily fixed, indicating the potential for remedial intervention later in development. Particularly important is evidence that recovery is associated with cognitive gains in some children. 

Another example comes from the qualitative data analysed by Gina Crivello and Ginny Morrow. The TAG encouraged us to seek examples of children who were ‘bucking the trend’ of expected negative outcomes despite their disadvantages. What was it about these children and their circumstances that made the difference, and how could this information be used to provide more enabling environments for children placed at risk by poverty? Gina and Ginny’s work, discussed here, found that it was a combination of mutually reinforcing factors such as child characteristics and enabling environments in the family and beyond which together diverted children at risk into positive pathways. They also found that to maintain this positive Development Cascade, the children needed sustained support through young adulthood. 

In sum, Tracing has synthesized evidence from across the study and combined it with life course longitudinal analyses that permit examination of the cumulative influence of sources of risk, protection and opportunity from across childhood and through adolescence. This approach has allowed us to consider the implications of these findings for child-focused policy and programmes as low- and middle-income countries strive to overcome intergenerational poverty and inequality and meet the challenges of the Sustainable Development Goals. We will share Tracing’s findings with policy makers and practitioners in government and non-government settings to help inform debates on how best to secure children’s well-being, development and rights. 

Tracing the consequences of child poverty is available digitally https://bit.ly/2TUOQRY and in print https://bit.ly/2U8vjwz.  For news of Young Lives you can follow us on Twitter @yloxford, Facebook, and check our website www.younglives.org.


The effect of early childhood stunting on children's cognitive achievements: Evidence from Young Lives Ethiopia

Early childhood development
Stunting and catch-up growth
Journal Article

In this article, the authors examine the effect early childhood stunting on cognitive achievements of children using longitudinal data that incorporate anthropometric measurements and results of cognitive achievement tests such as Peabody Picture Vocabulary Test and Cognitive Development Assessment quantitative tests. Their work is borne out of the context that there is little empirical evidence on the effect of childhood malnutrition on children’s cognitive achievements in low income countries like Ethiopia. Longitudinal data is therefore vital to understand the factors that influence cognitive development of children over time, particularly how early childhood stunting affects cognitive achievement of children up to the age of 8 years.

To access the journal, please visit: http://www.ejhd.org/index.php/ejhd/article/view/1234

Child undernutrition: opportunities beyond the first 1000 days

Nutrition, health and well-being
Early childhood development
Journal Article

Stunting often begins in utero and increases, on average, for at least the first 2 years after birth. The first 1000 days between conception and a child's second birthday has been identified as the most crucial window of opportunity for interventions.1 Evidence suggests that stunting is largely irreversible after the first 1000 days, leading to an intergenerational cycle of poor growth and development, in which women who were stunted in childhood remain stunted as adults and tend to have stunted offspring. However, evidence indicates that accelerated linear growth in childhood and adolescence following stunting in infancy (ie, catch-up growth) can occur. Evidence from the Young Lives international cohort study in Ethiopia, India, Peru, and Vietnam, found that around 50% of children who were stunted at age 1 year showed improvements in height and were no longer stunted at age 8 years in the absence of an intervention. Other longitudinal observational studies have also reported catch-up growth in childhood. Read the full article at the Lancet's website...

One, two, three star! Pre-school attendance and numeracy skills development

The potential of quality early childhood care and education to transform childrens’ lives is now widely recognised in research, in policy and in service delivery. Most significantly at a global level, the Sustainable Development Goal (SDG) Target 4.2 states that by 2030 countries should: ‘ensure that all girls and boys have access to quality early childhood development, care and pre-primary education so that they are ready for primary education’.

In 2005, when the Young Lives younger cohort were in pre-school, Ethiopia’s pre-school system was still emerging and dominated by private kindergartens for urban families.

Conversely, India already had a long-standing public pre-school system, but perceived quality weaknesses contributed to an increasing growth in a largely unregulated private pre-school sector.

Similarly, Peru also had a public pre-school system, but with the complexity of two distinct types of pre-school of different quality (CEI and PRONOEI). It also had a significant private preschool sector for better-off families, often seen as an entry point into better quality private schools.

Finally, Vietnam had a well-established public pre-school education system, integrated within the school system, and generally accessible, except to the most disadvantaged and marginalized minority groups.

According to Young Lives data, in 2006 pre-school attendance was almost universal for our sample in Vietnam (91 percent), Peru (89 percent) and the states of Andhra Pradesh and Telangana in India (87 percent) but very limited in Ethiopia (25 percent), and most of those children attended private pre-schools. In all countries, pre-school attendance was more common in urban areas and among wealthier households. A forthcoming report by my colleagues and I commissioned by the World Bank, documents the relationship between pre-school attendance and numeracy skills development over time, as measured at the age of 5, 8 and 12. While causal relationship cannot convincingly be established within the confines of the report, we provide suggestive evidence on the positive role of preschool for skills development, particularly in Vietnam and in Ethiopia, respectively the country with the highest and the lowest pre-school enrolment.

Does household access to improved water and sanitation in infancy and childhood predict better vocabulary test performance ?

Access to services
Early childhood development
Water and sanitation
Journal Article


Test associations between household water and sanitation (W&S) and children's concurrent and subsequent Peabody Picture Vocabulary Test (PPVT) scores.

Primary outcome measures

PPVT scores at 5 and 8 years. Key exposure variables were related to W&S, and collected at 1, 5 and 8 years, including ‘improved’ water (eg, piped, public tap or standpipe) and ‘improved’ toilets (eg, collection, storage, treatment and recycling of human excreta).


Access to improved water at 1 year was associated with higher language scores at 5 years (3/4 unadjusted associations) and 8 years (4/4 unadjusted associations). Ethiopian children with access to improved water at 1 year had test scores that were 0.26 SD (95% CI 0.17 to 0.36) higher at 5 years than children without access. Access to improved water at 5 years was associated with higher concurrent PPVT scores (in 3/4 unadjusted associations), but not later scores (in 1/4 unadjusted associations). 5-year-old Peruvian children with access to improved water had better concurrent performance on the PPVT (0.44 SD, 95% CI 0.30 to 0.59) than children without access to improved water. Toilet access at 1 year was also associated with better PPVT scores at 5 years (3/4 unadjusted associations) and sometimes associated with test results at 8 years (2/4 unadjusted associations). Toilet access at 5 years was associated with concurrent PPVT scores (3/4 unadjusted associations). More than half of all associations in unadjusted models (water and toilets) persisted in adjusted models, particularly for toilets in India, Peru and Vietnam.


Access to ‘improved’ water and toilets had independent associations with children's PPVT scores that often persisted with adjustment for covariates. Our findings suggest that effects of W&S may go beyond subacute and acute infections and physical growth to include children's language performance, a critical component of cognitive development.

Download Does household access to improved water and sanitation in infancy and childhood predict better vocabulary test performance in Ethiopian, Indian, Peruvian and Vietnamese cohort studies?  Kirk A Dearden, Alana T Brennan, Jere R Behrman, Whitney Schott, Benjamin T Crookston, Debbie L Humphries, Mary E Penny, Lia C H Fernald 

Early Investment in Preschool and Completion of Secondary Education in Ethiopia: Lessons From Young Lives

Early childhood development
Early education
Working paper

Investments in early childhood education are believed to be critical in forming the foundation for life-long learning and providing children with the opportunity to reach their full potential. This is because early childhood is a crucial phase of growth and development, where early circumstances can influence outcomes across the entire course of an individual’s life.

Despite the plethora of studies in high-income countries, little is known about the long-term contributions of early childhood investment in low-income countries. To the best of our knowledge, there is no longitudinal study in Ethiopia that has looked at the contribution of preschool education beyond primary school-aged children. The study that this working paper reports on aimed to fill this research gap by using longitudinal data from Young Lives in Ethiopia to look at the long-term estimates of early childhood education on successful completion of secondary education and the chance of transitioning to institutions of higher learning.

As the data showed a huge divide in preschool access between urban and rural children, we used only the urban sample in our logit models. Findings indicate that urban preschool children are 25.7 per cent more likely to complete secondary education than their non-preschool counterparts at the proper age. The marginal returns are higher for those who attended preschool for two and three years than those who only attended for one year. In particular, those who attended for three years have a higher probability of transitioning to higher education at the age of 18.

Overall, the findings suggest that a significant part of children’s educational inequalities at later ages are explained by the level of early childhood investment. In spite of such significance, public investment to this subsector of the education system is meagre, relative to the other subsectors. Based on the current preschool landscape of Ethiopia, only a quarter of the 7.4 million preschool-aged children – mainly from better-off families and urban areas – are able to make their way to this vital learning stage. Most children simply begin primary school without any exposure and consequently face considerable difficulties on their educational pathways in completing secondary education and transitioning to institutions of higher learning.

The analysis suggests that if the aim is to reduce educational inequality among future generations and to be able to conquer poverty in the years ahead, equalising the quality of early education, with two to three years of preschool exposure for both urban and rural children aged 4 to 6 years old, will remain an essential educational policy for Ethiopia.


Scaling-up Early Learning in Ethiopia: Exploring the Potential of O-Class

Early childhood development
Early education
Working paper

SDG Target 4.2 identifies ‘pre-primary education’ as a strategy to strengthen school readiness and contribute to the quality and outcomes of education, which is supported by the powerful evidence from evaluation research. The challenge faced by many countries is to deliver the proven potential of well-planned, quality programmes to scale. This working paper summarises Ethiopia’s growing commitment to pre-primary education and reports recent Young Lives engagement with the Ministry of Education in Ethiopia and other partners to support scale-up. Ethiopia’s most recent ambitious targets for early learning have been set out in the Fifth Education Sector Development Programme (ESDP V 2015), with pre-primary classes (known as O-Class) within primary schools being seen as the most rapid route to scale-up.

The paper reports on the progress and the challenges in delivering ambitious targets. We report key findings from exploratory fieldwork on two key themes, namely the response of Regional Education Bureaus in planning, financing, management and ensuring human capacity for scale-up; and the potential of Ethiopia’s Colleges of Teacher Education to supply sufficient trained teachers to work with young children, especially in the rapidly expanding O-Classes. 

The final section draws on parallel experiences of other countries, notably Grade R in South Africa, and reports on six key challenges for scale-up; equity; age-appropriateness; cross-sectoral coordination; capacity building; and research and evidence. Other key challenges go beyond the scope of this working paper, notably the models for governance and financing that can deliver quality early education for all. While Ethiopia’s initiative to scale-up O-Class is a welcome indicator of policy commitment to SDG Target 4.2, we conclude that there is a risk that low quality pre-primary programmes will not deliver on the potential of early childhood education and that children (especially poor children) will be the losers.

Inequality, preschool education and cognitive development in Ethiopia: Implication for public investment in pre-primary education

Early childhood development
Early education
Journal Article

This study used longitudinal data from the Young Lives project in Ethiopia to examine the main factors relating to preschool access and their potential effects on cognitive performance of children aged five and eight years. The results show that only one quarter of the preschool-aged children have the opportunity to attend this vital stage of education, with significant disparities by family wealth, education and regional location. Regardless of its limited coverage, preschool attendance is shown to have statistically significant positive effects on cognitive performance, measured by receptive vocabulary and mathematics tests. The effects do not also seem to fade away at a later age, as the inequality in cognitive abilities at age five continues to exist at the age of eight. Furthermore, using mediation analyses, causal chains between family backgrounds and cognitive performance were thoroughly analysed. Bootstrap results show that preschool attendance mediates about one third of the direct effects of family wealth, education and regional location on child cognitive performance.

Nevertheless, despite the importance of preschool education, public investment in this area is currently very limited, with the private sector taking the key role and exacerbating the inequality that exists between children of the rich and poor. These findings thus emphasize the need for government involvement in the form of public investment to this subsector to increase access for all children and reduce future educational inequalities.


Preschool education, cognitive development, inequality, Ethiopia

The Impact of Child Malnutrition and Health on Cognitive Skills in Ethiopia: Using a Standard Panel Data Analysis

Early childhood development
Malnutrition and cognitive development
Book / chapter

Over the past two decades, Ethiopia has made significant progress in key human development indicators. Child mortality and nutrition have improved and primary school enrolments have increased.

This study uses longitudinal data of 1813 strong younger cohort and 443 of the older cohort—children in five regions in the country over two rounds from the Young Lives Survey. The purpose of this study is to explore the effects of child nutrition and health on their cognitive achievements measured by the Peabody Picture Vocabulary Test (PPVT) test score using a static panel model. The regression analysis shows that there is a positive association between child nutrition (measured by height-for-age WHO z-scores) and cognitive achievements in all age cohorts.

This study also finds that, there are cognitive skill disparities among regions and between sexes and areas of residence. Therefore, the government must give due attention to the importance of nutrition for cognitive and educational development, and these must be integrated as a key component of early childhood care and development programs Since there are regional, residence, and gender disparities in the cognitive skills of the children in each cohort an appropriate nutritional strategy must be developed. In order to achieve long-run human capital development in Ethiopia, all domestic and international nongovernmental organizations have to support and finance the national plan to scale up the nutritional status of children in their early ages.


Child nutrition, Cognitive skills, Panel data analysis


Download  The Impact of Child Malnutrition and Health on Cognitive Skills in Ethiopia: Using a Standard Panel Data Analysis, Kahsay Berhane Lemma in Poverty and Well-Being in East Africa,A Multi-faceted Economic Approach, editor Almis Heshmati