1990 or beyond. Interventions are categorized into five groups: (i) economic interventions which include conditional and unconditional cash and/or food transfers, vouchers for private schools, microfinance opportunities, school fee reductions or eliminations, school scholarships or fellowships, and material support such as school uniforms; (ii) educational programs and practices providing services or materials to students, providing extra teachers, reducing class sizes, providing incentives to teachers, monitoring teacher attendance, training teachers, empowering and funding parent school associations, or covering more comprehensive school reform and improvement efforts; (iii) interventions related to health care and nutrition; (iv) building programs and infrastructure improvements; and (v) interventions providing information or training to students, parents or whole communities.

In their meta-analysis, Petrosino et al. (2012) mainly concentrate on two outcome variables, enrollment and attendance. They find that the largest impacts on these two variables are achieved by interventions entailing the construction of new schools or the improvement of school infrastructure. Relatively large enrollment and attendance effects can also be documented for interventions related to health care and nutrition, and economic practices and programs. In contrast, impacts are generally found to be small for those interventions that provide information or training or for those that reform educational practices or programs. Overall, the results of the systematic review and meta-analysis by Petrosino et al. (2012) are very consistent with our findings for South Asia. In particular, evidence for South Asia discussed above confirms that the establishment of new schools can dramatically increase enrollment levels. Besides, we also conclude for South Asia that at least some of the interventions categorized by Petrosino et al. (2012) as belonging to the group of economic practices and programs – like CCT programs – have a demonstrated ability to significantly increase school enrollment and attendance.

The main objective of the systematic review and meta-analysis by Krishnaratne, White and Carpenter (2013) is to find out whether education-related interventions are effective in improving learning outcomes in developing countries. The respective meta-analysis is based on 75 experimental or quasiexperimental studies from all over the developing world. Its overall conclusion is that educationrelated interventions _do_ work. When it comes to a more thorough analysis of this result, “while this review provides a relatively detailed narrative of the variation in program effects within the body of the paper, the statements on ‘effective’ or ‘ineffective’ interventions in the conclusions section are based on relatively little data” (Conn, 2014, p. 10). Moreover, the focus of Krishnaratne, White and Carpenter (2013) is clearly on a more verbal discussion of different interventions’ impacts on the one hand and the meta-analysis of education-related interventions’ overall effect on the other hand. In contrast, a rigorous meta-analysis that compares the relative impacts on learning levels of different types of education-related interventions is only touched upon. This makes it difficult to compare our detailed findings for different groups of interventions with those of Krishnaratne, White and Carpenter (2013).

Many more details on the relative effectiveness of different types of interventions in improving learning outcomes are provided by the systematic review and meta-analysis by McEwan (2014). This review and meta-analysis is based on 77 interventions that fulfill the following criteria: (i) an

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