Economists have generally thought that the answer was not much. Great teachers and early childhood programs can have a big short-term effect. But the impact tends to fade. By junior high and high school, children who had excellent early schooling do little better on tests than similar children who did not — which raises the demoralizing question of how much of a difference schools and teachers can make.
There has always been one major caveat, however, to the research on the fade-out effect. It was based mainly on test scores, not on a broader set of measures, like a child’s health or eventual earnings. As Raj Chetty, a Harvard economist, says: “We don’t really care about test scores. We care about adult outcomes.”
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