Heckman, James; Hohmann, Neil; Smith, Jeffrey; Khoo, Michael - In: The Quarterly Journal of Economics 115 (2000) 2, pp. 651-694
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...