imPact evaluation seRies no. 28

bl ic Di sc lo su re A ut ho riz ed Pu bl ic Di sc lo su re A ut ho riz ed Pu bl ic Di sc lo su re A ut ho riz ed Pu bl ic Di sc lo su re A ut ho riz ed Produced by the Research Support Team The Impact Evaluation Series has been established in recognition of the importance of impact evaluation studies for World Bank operations and for development in general. The series serves as a vehicle for the dissemination of findings of those studies. Papers in this series are part of the Bank’s Policy Research Working Paper Series. The papers carry the names of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely those of the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank and its affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent. Policy ReseaRch WoRking PaPeR 4784 Large-scale randomized interventions have the potential to uncover the causal effect of programs applying to a large population, thereby improving on the insights gained from currently dominant smaller randomized studies. However, the external validity gained through larger interventions typically implies less supervision and often comes at the cost of some deviation from the randomization plan. This paper investigates the impact of the Nutrition Enhancement Program, which aims to improve child nutrition in Senegal based on a large-scale randomized community intervention. The analysis explicitly deals with deviation from the planned treatment and suggests approaches for combining ex-post adjustments such as propensity score matching with the This paper—a product of the Human Development and Public Services Team, Development Research Group—is part of a larger effort in the department to understand the impact of investments in health and nutrition. Policy Research Working Papers are also posted on the Web a