The state of preschool evidence: findings from reviews of (quasi) experimental research

• In Event: Pre-primary education: luxury or necessity?

Proposal

As the number of children around the world who have access to preschool rises, so have the number of studies on the impacts of provision and quality improvements on children’s learning from low, middle, and high-income countries. This literature comes from multiple disciplines, including Developmental Psychology, Economics, and Education, and examines interventions that vary in important ways, including their objectives, target population, and implementation context. Extracting lessons from these studies is important to better understand the returns to pre-primary investments and identify effective strategies that improve learning. We will share key findings from two ongoing reviews of recent rigorous evidence of the impacts of center-based early childhood education interventions targeting children aged 3 to 6.
The first is a meta-analytic review that documents 56 experimental and quasi-experimental estimates of the effectiveness of expansions in preschool coverage and improvements in quality across high-, middle-, and low-income countries. We report whether interventions generated statistically and economically important impacts on primary school coverage; child development, school readiness, total educational attainment, and wellbeing in adulthood; and parents and teachers-related outcomes. We extract interventions’ implementation features, such as the profile of teachers, school fees, and characteristics of the targeted population, and assess whether variation in these features we can observe correlates with impact.
We use the range of estimates of impact from these 56 studies and available estimates of costs from a subset of the studies and the extant literature to provide a range of returns to investments in expanding preprimary coverage and in improving its quality, following the methods of Galasso and Wagstaff (2019) and Hollands et al (2016). Given the number of remaining research questions that are still unaddressed in low and middle income countries (e.g., should preprimary educators come from a professional cadre of qualified teachers, should preprimary curricula be play-based) we also compare the benefits of learning the answers to these questions to the corresponding costs of setting up randomized control trials, following the decision-theoretic framework of Muralidharan et al (2017).
The second is a review of 18 reviews of studies on the impacts of preschool provision and quality improvements on children’s learning. In this study, we analyze areas of convergence and divergence in these reviews’ conclusions, synthesizing a substantial body of evidence (1025 underlying studies). We extract conclusions from each review and the underlying individual studies that drive those conclusions. We also document features of the reviews that might influence their results, including geographical focus, methodological approach, and inclusion criteria. We then identify where reviews conclusions align and where they diverge in their analysis and conclusions, and examine the reasons behind this divergence, including features of each review, as well as potential inclusion and exclusion errors associated with how reviews categorize and aggregate outcomes and interventions. Finally, we document areas of overlap in the recommendations of existing reviews of which interventions more effectively improve cognitive, social-emotional and behavioral outcomes, as well as long-term educational attainment and teaching quality.

Authors

• Maria Magdalena Bendini, The World Bank

• Alaka Holla, Strategic Impact Evaluation Fund

• David K. Evans, Center for Global Development

• Sharon Wolf, University of Pennsylvania