Substitution and dropout bias in social experiments: A study of an influential social experiment

• 成果类型: Article; Proceedings Paper
• 署名作者: Heckman, J; Hohmann, N; Smith, J; Khoo, M
• 署名单位: University of Chicago; National Bureau of Economic Research; Western University (University of Western Ontario)
• 刊物名称: QUARTERLY JOURNAL OF ECONOMICS
• ISSN/ISSBN: 0033-5533
• DOI: 10.1162/003355300554764
• 发表日期: 2000
• 页码: 651-694
• 关键词: econometric evaluation estimator; PROGRAM EVALUATIONS

摘要

This paper considers the interpretation of evidence from social experiments when persons randomized out of a program being evaluated have good substitutes for it, and when persons randomized into a program drop out to pursue better alternatives. Using data from an experimental evaluation of a classroom training program, we document the empirical importance of control group substitution and treatment group dropping out. Evidence that one program is ineffective relative to close substitutes is not evidence that the type of service provided by all of the programs is ineffective, although that is the way experimental evidence is often interpreted.