Dylan Matthews interviews Harvard professor Raj Chetty about a subject I blogged on a couple of weeks ago. Better early childhood education, it turns out, might not directly affect scores on standardized tests (or on things like IQ tests), but it apparently does affect other behaviors that are strongly related to higher incomes later in life:
One thing I found interesting about the effect of test scores as relates to earnings is that it seems like some of the gains you find in early childhood, that might not show up on later test scores, later emerge when you're looking at earnings data.
Yes, and that's in fact, I think, the most striking finding....[Test scores] fade out over time. So kids who had better teachers and were in smaller classes in kindergarten aren't doing all that better, really, on tests in middle school and high school. But what's surprising is that those effects reemerge in adulthood. And I can talk about why we think that is.
Why do you think that is?
One explanation for this fadeout and then reemergence of the impact of kindergarten is through non-cognitive channels. [...] For a limited subset of the students we have measures of non-cognitive ability in eighth grade. So what that means is measures like, they ask teachers to evaluate whether the students are being disruptive in class, whether the students are putting in a lot of effort, whether they're motivated and so on. Now, we find persistent effects of your kindergarten class on these non-cognitive measures. There's no fadeout, or very little fadeout on the non-cognitive stuff.
So one potential explanation of all of the findings together is, a good kindergarten teacher teaches you the material that you're tested on in kindergarten, and so you do well on kindergarten tests. That same good teacher also imparts non-cognitive skills, like they teach you how to be a disciplined learner, how to put in a lot of effort, how to be patient....It's quite intuitive that these non-cognitive skills matter when you're an adult. It helps to get a good job and to do well in general if you're a disciplined person, if you're perseverant and so on.
Bottom line: school matters, and the way it matters doesn't get picked up entirely via standardized testing. In modern society, there are lots of behavioral traits that are just as important as IQ and subject matter knowledge. But we only test for subject matter knowledge, and so it gains an outsize importance.