Background:This article describes eight flaws that occur in impact evaluations.Method:The eight flaws are grouped into four categories on how they affect impact estimates: statistical imprecision; biases; failure of impact estimates to measure effects of the planned treatment; and flaws that...

Background:Impact evaluations draw their data from two sources, namely, surveys conducted for the evaluation or administrative data collected for other purposes. Both types of data have been used in impact evaluations of social programs.Objective:This study analyzes the causes of differences in...

In spite of exhaustive research by many analysts on the data generated by the NIT experiments, uncertainty remains over whether work reductions in the experiments should be considered "large" or "small." The authors of this paper argue that this uncertainty arises in part because different...

This paper explores the gains from multiplying the number of sites used in experimental evaluation of the effects of employment and training programs. Using a multilevel (hierarchical) statistical framework, the authors analyze the role of site multiplication in three recent program evaluations....

An important source of errors in transfer payments programs is the fraudulent misreporting of earnings received by recipients. We propose a model of the recipient's decision to report income and the expected penalties if caught engaging in fraud. We discuss several features of the detection and...