Disagreement over the Evaluation of a Controlled Experiment

Under the leadership of the U.S. Department of Labor, the states of Texas and Georgia engaged in what was perhaps the most careful large-scale randomized controlled experiment ever conducted in a natural setting. It was designed to test the widely supported theory that the recidivism rate of ex-convicts could be reduced or retarded by providing them for a time with a monthly monetary allowance. During the evaluation of the experiment, a radical difference of opinion over the correct interpretation of its results arose between the evaluators (Peter H. Rossi, Richard A. Berk, and Kenneth J. Lenihan) and Hans Zeisel, a member of the advisory board. This article, together with the comment and reply that follow it, explicates this difference and attempts to resolve it.