"Follow-up assessment of the participants involved in the project has been completed. Progress was monitored at ages 3, 4, 5, 6.5, 8, 12, 15 and 21. The areas covered were cognitive functioning, academic skills, educational attainment, employment, parenthood, and social adjustment. The significant findings of the experiment were as follows:
Impact of child care/preschool on reading and math achievement, and cognitive ability, at age 21:
An increase of 1.8 grade levels in reading achievement
An increase of 1.3 grade levels in math achievement
A modest increase in Full-Scale IQ (4.4 points), and in Verbal IQ (4.2 points).
Impact of child care/preschool on life outcomes at age 21:
Completion of a half-year more of education
Much higher percentage enrolled in school at age 21 (42 percent vs. 20 percent)
Much higher percentage attended, or still attending, a 4-year college (36 percent vs. 14 percent)
Much higher percentage engaged in skilled jobs (47 percent vs. 27 percent)
Much lower percentage of teen-aged parents (26 percent vs. 45 percent)
Reduction of criminal activity"
The project concluded that high quality, educational child care from early infancy was therefore of utmost importance."
Abecedarian Early Intervention Project - Wikipedia, the free encyclopedia
If you have a rational critique of the experiment I haven't been able to identify it.