explore the sensitivity of results to the score scale.

# **4 Results**

## **4.1 Aggregate categories of policies and interventions**

We are interested in comparing the impacts of aggregate categories of policies and interventions. To this end, we summarize results by category of education intervention, such as Early Childhood Development (ECD) or instruction targeted to the child’s level of learning rather than grade level. Intervention categories are based on original study designations, with a few adjustments. These adjustments help classify interventions more precisely based on the primary theory of change underlying them. First, we recategorize technology interventions into either “targeted instruction” or “additional inputs alone” based on whether they involved adaptive software or were largely a hardware-based intervention. Second, we classify interventions for ECD that involved building or opening of schools or classrooms as “targeted intervention to reduce travel time to schools.” Third, we define teacher training interventions narrowly. Many interventions include training of teachers; for this analysis, when a program provides materials to help teachers target instruction to the level of the child and also provides training to those teachers, we classify that as a “targeted instruction” intervention. “General-skills teacher training” captures only general teacher training programs without other major elements. Fourth, for interventions with multiple components, we selected the central component and used that as a category. Later in the paper, we examine individual studies and so will characterize them more precisely.

Comparative information on effectiveness will be most useful to policymakers when it incorporates information about cost. Therefore, we start by analyzing cost-effectiveness of policies and interventions with a subset of studies where cost information is available. Figure 3 shows the LAYS gained per $100 per child.<sup>11</sup> To calculate this, we divide the per-student gains by the per-student costs, so the figure shows LAYS gained per student per $100 spent per student. Typical spending in education systems ranges between $208 per student in Sub-Saharan Africa to $7,908 in East Asia in primary school in terms of 2013 PPP USD (Bashir et al. 2018). Therefore, cost-effectiveness per $100 per student is a relevant unit for many systems, along the lines of status-quo spending benchmarks, even at the lower tail of spending. Of course, the share of overall investment that $100 represents will depend substantially on context.

The top performers, ranked by mean effect size, are: targeted information campaigns on benefits, costs and quality; interventions to target teaching instruction by learning level rather than grade (such as “Teaching at the Right Level” interventions and tracking interventions); improved pedagogy in the form of structured lesson plans with linked materials and monitoring (which includes combination interventions such as Tusome in Kenya); community involvement in school

> 11In Appendix C we complement our data with data from the 2023 GEEAP updated report (Akyeampong et al., 2023) and show cost-effectiveness results in Figure C1.

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