A lot can be learned about the impact of an antipoverty program by studying income replacement for those observed to leave the program after its retrenchment. A Bank-supported workfare program in Argentina is found to have a sizeable impact on participants' incomes

"The author critically reviews the methods available for the ex-post counterfactual analysis of programs that are assigned exclusively to individuals, households, or locations. The discussion covers both experimental and non-experimental methods (including propensity-score matching,...