This study uses meta-analysis to synthesize findings from 31 evaluations of 15 voluntary government-funded training programs for the disadvantaged that operated between 1964 and 1998. On average, the earnings effects of the evaluated programs seem to have been largest for women, quite modest for men, and negligible for youths. For men and women, the earnings effects of training appear to have persisted for at least several years after the training was complete. Classroom skills training was apparently effective in increasing earnings, but basic education was not. There is no evidence that more expensive training programs performed better than less expensive ones. Although the United States has more than three decades of experience in running training programs, the programs do not appear to have become more effective over time.
A meta-analysis of government-sponsored training programs. By David H. Greenberg, Charles Michalopoulos, and Philip K. Robins. Vol. 57, No. 1 (Oct. 2003), pp. 31-53.