The third way to categorize interventions that was introduced in section 2 relied on whether a specific intervention emphasized the provision of additional resources or aimed to alter individual or collective incentives. As outlined above, there is no direct correspondence between this third categorization and the four actors (teachers, schools, households and communities). For each of the actors, a particular intervention might provide resources or alter incentives. Of course, this does not render meta-analyses of native language, mathematics or overall learning outcomes with interventions grouped according to whether they primarily address inputs or incentives unfeasible. However, such meta-analyses fail to find any statistically significant differences in learning effects between the two groups of interventions.<sup>11</sup>

# **3.3. Discussion**

As already mentioned in the introduction, the last ten years have seen a dramatic rise in the number of rigorous impact evaluations of education-related interventions in developing countries. While in South Asia we have the unique benefit of having relatively plentiful and high-quality impact evaluations, our paper is not the first to combine a systematic literature review with a rigorous metaanalysis of the available evidence to investigate what kind of interventions are most effective in improving education outcomes. In fact, as also already spelled out in the introduction, four methodologically similar reviews exist. One of these four reviews (by Petrosino et al., 2012) centers primarily on school enrollment and attendance. The other three (by Krishnaratne, White and Carpenter, 2013; Conn, 2014; and McEwan, 2014) are mainly concerned with students’ learning outcomes. Another differentiating factor among the four reviews is that Petrosino et al. (2012), Krishnaratne, White and Carpenter, (2013) and McEwan (2014) consider evidence from all over the developing world while Conn (2014) concentrates on Sub-Saharan Africa, a region that shares many similarities with South Asia but also exhibits a number of important differences.

Reassuringly, the results of our systematic review and meta-analysis are generally very consistent with the findings from the four other methodologically comparable works. Nevertheless, there are instances where education-related interventions have apparently had different impacts in South Asia and other parts of the developing world.

The systematic review and meta-analysis of Petrosino et al. (2012) includes the universe of studies that (i) assess the impact of an intervention on primary or secondary school outcomes, (ii) use an experimental or quasi-experimental approach, (iii) are conducted in a developing country, (iv) include at least one quantifiable education-related outcome measure (like enrollment, attendance, dropout, or progression), (v) are published or made available before December 2009, (vi) and include data from

> 11 Appendix C contains the forest plots of three meta-analyses of interventions’ impacts on composite test scores where interventions are not grouped by actor but by whether they primarily target individuals or a collective, address education supply or demand, or provide resources or incentives. In addition to that, the appendix also shows outputs of metaanalyses that rely only on impact estimates derived from RCTs or group studies by whether or not at least one author was affiliated with the World Bank at the time of the study’s publication.

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