In Project STAR, 11,571 students in Tennessee and their teachers were randomly assigned to different classrooms in their schools from kindergarten to 3rd grade. Researchers learned that kindergarten test scores are highly correlated with such outcomes as earnings at age 27, college attendance, home ownership, and retirement savings. Students who were randomly assigned to small classes are significantly more likely to attend college, attend a higher-ranked college, and perform better on a variety of other outcomes. Students who were assigned to higher-quality classrooms (for example, with better teachers) have higher earnings, college attendance rates, and other outcomes. These long-term impacts are especially surprising because the effects of kindergarten class quality fade on test scores in later grades. The authors conclude that early childhood education has substantial long-term impacts, potentially through noncognitive channels.
Chetty, Raj, John N. Friedman, Nathaniel Hilger, Emmanuel Saez, Diane Whitmore Schanzenbach, and Danny Yagan. "$320,000 Kindergarten Teachers." Phi Delta Kappan 92.3 (November 2010): 22-25.