Critics of investment in quality early childhood education like to point to studies that show test scores of the kids who attend preschool or full-day kindergarten start out strong but fade over time to match those of kids who didn't.

The New York Times reports that the "fairly explosive" findings of a new economic study put a lie to the "fade-out effect."

"We don't really care about test scores. We care about adult outcomes," says Raj Chetty, one of the Harvard economists behind the study.

What he and other researchers found is far more than important than an eighth-grade ISTEP+ score. They tracked the path of 12,000 Tennessee children who had participated in a kindergarten experiment in the 1980s and found that those who had a strong early learning experience were more likely to go to college, less likely to become single parents, more likely as adults to be saving for retirement and earning more overall.

"The economists don't pretend to know the exact causes," according to the Times. "But it's not hard to come up with plausible guesses. Good early education can impart skills that last a lifetime -- patience, discipline, manners, perseverance. The tests that 5-year-olds take may pick up these skills, even if later multiple-choice tests do not."

And here's a thought to thrill (or maybe depress) early childhood educators: "Mr Chetty and his colleagues ... estimate that a standout kindergarten teacher is worth about $320,000 a year. That's the present value of the additional money that a full class of students can expect to earn over their careers. This estimate doesn't take into account social gains, like better health and less crime."