that combined water arsenic testing with education regarding health implications of chronic arsenic exposure and methods to limit exposure, reduced arsenic exposure provided there were arsenics-safe drinking water sources available (George et al., 2012).

The study on the performance of the police force in Rajasthan, India, already mentioned above also provides evidence pointing to the limited effectiveness of interventions that solely rely on the provision of information to collectives on the demand side: when community observers were randomly placed in certain police stations, this did not have any robust impacts on police performance or the public’s perception of the police. The intervention’s failure was likely due to constraints on local implementation (Banerjee et al., 2012).

# **3.2. Meta-Analysis**

A meta-analysis relies on statistical techniques to combine results from two or more individual interventions. The objective is to improve the precision of estimated treatment effects and to assess whether these treatment effects vary for different types of interventions (Egger, Davey Smith and Phillips, 1997). Thus, meta-analyses are an ideally suited tool to utilize the education interventions in South Asia reviewed in the last section to derive rigorous and robust policy recommendations.

In the context of a meta-analysis, four methodological issues are of paramount importance: (i) the selection of the underlying evidence, (ii) the grouping of individual interventions, (iii) the weighting of the evidence, and (iv) the selection of adequate outcome measures.

- (i) With regard to the selection of the underlying evidence, the meta-analyses described here are based on the set of studies listed in Table A. That is, only those 29 studies are included in the meta-analyses that evaluate the impact of a clearly-defined education-related intervention on an equally well-defined education-specific outcome variable, contain data for at least one South Asian country, and satisfy strict quality and reporting criteria.

- (ii) Based on the conceptual framework introduced in section 2, interventions are grouped according to the primary actor that is targeted by intervention. Therefore, the meta-analyses distinguish between four types of interventions: Those addressing teachers, schools, households and communities, respectively. Indirectly, this also allows an assessment of whether interventions addressing education supply (teachers and schools) or demand (households and communities) appear more successful in raising education outcomes and if programs targeting individuals (teachers and households) or those addressing collectives (schools and communities) have shown greater promise. The exact mappings of interventions into these categories are again listed in Table A.

- (iii) Standard errors of interventions’ impacts are used for weighting the evidence. In other words, interventions for which impacts have been more precisely estimated are given larger weights as compared to those interventions where the exact size of the impact is less clear.

- (iv) Adequate outcome measures should be pertinent to the question under study, widely used in the relevant literature, and easily comparable across different interventions. For these reasons,

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