Replication of ‘Worms: Identifying Impacts on Education and Health’


Replication Researcher: Alexander Aiken (with Calum Davey)
Original Paper Title: Worms: Identifying Impacts on Education and Health in the Presence of Treatment Externalities
Original Researchers: Edward Miguel and Michael Kremer
Original Publication: Econometrica
Replication Plan: Aiken’s Replication Plan
Current Status: Completed Replication Study


The Original Study

This study evaluates the impact of a deworming programme in Kenya on health and education outcomes. It highlights the importance of accounting for positive treatment externalities, as failing to do so leads evaluators to severely underestimate the impact. By improving overall health, the mass treatment of children aims to increase their participation and performance in school. Overall lower infection prevalence also benefits untreated children in school and in surrounding communities. The authors estimate these positive externalities to consider them in their final cost-benefit analysis.

The Replication

This replication study of Miguel and Kremer (2004) reexamines their highly influential work on the impact of worm treatment medication on children's health and educational outcomes. As worm infections remain extremely common and deworming treatments are both cheap and highly effective, if there were proven benefits associated with deworming, this could potentially lead to huge impacts in global public health programs, especially in children in developing countries. The general subject of the broader economic impacts of public health programs and how to assess these is also of great current interest. Cluster randomised trials (CRTs) are a powerful methodology for investigating such impacts, but require appropriate statistical handling to reach appropriate conclusions. However, randomised trials rarely make assessment of the benefits that accrue from spillover of the effects of an intervention – this study highlights the risks and benefits of such an analytic approach.The original analysis for this study was based on econometric approaches and used a language and format that would be unfamiliar to many healthcare researchers – this may account for the limited appreciation of the study amongst “health academics” in general and epidemiologists in particular. The study aims to re-frame the analysis of this data in an “epidemiological” format, thus making it accessible to a wider readership.

Replication plan (709.2 KB)

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