Ravallion, Martin, Emanuela Galasso, Teodoro Lazo, Ernesto Philipp. 2005. “What Can Ex-Participants Reveal about a Program’s Impact?” Journal of Human Resources 40(1): 208-230.

We propose a method for estimating the mean impact of an assigned social program when it is not feasible to do a pre-intervention baseline survey but it is feasible to track ex-participants. In our triple-difference estimator, measured outcome changes are compared between continuing participants and matched ex-participants, after netting out the outcome changes for a matched comparison group who never participated. With sufficient followup observations one can test the joint conditions required for correctly identifying the gains to current participants. We apply the method to a workfare program in Argentina. Significant impacts on participants’ current incomes are revealed.

Martin Ravallion and Emanuela Galasso are with the Development Research Group at the World Bank. Teodoro Lazo and Ernesto Philipp are with the Trabajar project office of the Ministry of Labor, Government of Argentina. The work reported in this paper is part of the ex-post evaluation of the World Bank’s Social Protection III Project in Argentina. The authors’ thanks go to staff of the Trabajar project office in the Ministry of Labor, Government of Argentina, who have helped in countless ways, and to the Bank’s Manager for the project, Polly Jones, for her continuing support of the evaluation effort, and many useful discussions. The authors also benefited from comments from Hide Ichimura, Jyotsna Jalan, two referees, and seminar participants at Boston University, Columbia University, University College London, Yale University, the Network on Inequality and Poverty of the Latin American and Caribbean Economics Association, and the World Bank. Support from the Evaluation Thematic group of the World Bank’s Poverty Reduction and Economic Management Network is gratefully acknowledged. The data used in this article can be obtained from the authors. These are the views of the authors, and need not reflect those of the Government of Argentina or the World Bank. Correspondence: Martin Ravallion, World Bank, 1818 H Street NW, Washington DC, 20433 USA; <mravallion@worldbank.org>.