(2022-01-25) Smith Pre K Is Day Care

Noah Smith: Pre-K is day care. There’s an interesting new psychology paper out about the benefits of universal pre-kindergarten education. The results are not encouraging

This is an important issue right now, because “universal” preschool for 3- and 4-year-olds is part of the Build Back Better plan that Biden is trying (with difficulty) to push through the Senate right now

The study above is a very good one

But at the end of the day, even a very good study is just one study.

So you really have to look at a whole bunch of studies, of a whole bunch of programs, in a whole bunch of places

So, I’ll go through a good bit of that evidence here. But first, a preview. The upshot is that really high-quality pre-K programs do provide some educational benefit. But for the kind of mass-market pre-K programs that Biden’s plan would involve, the educational benefits are probably close to nil, and for many kids are probably negative.

BUT, the reason pre-K often hurts education is that kids learn even better when their parents are at home tutoring them all day.

government-funded free pre-K frees parents to go work in the market and earn money for their families.

Why people think pre-K works: Theory and some evidence

Jim Heckman is a very accomplished empirical economist; he won the Nobel Prize for figuring out ways to reduce selection bias in empirical studies.

Heckman’s own research finds good efficacy for early childhood interventions

a 2017 meta-analysis by McCoy et al. looked at 22 studies of early childhood education published between 2007 and 2016, and found modest but statistically significant benefits for graduation rates, grade retention, and placement in special education

But note that not all programs are created equal.

Meanwhile, there’s a pretty big literature looking at the long-run effects of the Head Start program, which provides education, health services, and other services to poor kids in the U.S. These studies generally report positive results.

Head Start participants gain 0.23 standard deviations on a summary index of young adult outcomes. This closes one-third of the gap between children with median and bottom quartile family income, and is about 80 percent as large as model programs such as Perry Preschool

*But a deeper look at the literature reveals that this conclusion comes with some major caveats:

Not all pre-K programs are created equal; some end up having no effect or even harming student outcomes

Effects on academic performance are much weaker than effects on other life outcomes

Effects aren’t generally equal across students; pre-K appears to help the disadvantaged more*

it may just be that this particular program wasn’t very good. A 2018 study — also Lipsey et al., but with different coauthors — also found harmful results from the same Tennessee program.

Another example is Quebec’s universal child care program. Baker, Gruber & Milligan (2019) find that this program had lasting negative effects on outcomes like health, crime rates, and life satisfaction.

Second, even when studies do find positive effects, these effects sometimes disappear over time. And the cognitive and academic benefits tend to disappear much faster than other benefits like health and achievement

So cognitive benefits tend to fade, but social and psychological benefits often last — as long as the programs are good ones, which not all of them are.

So which programs are good ones? Here we run into another problem: As pre-K programs get more and more universal, they seem to be falling in quality. Pre-K has problems scaling up.

A persistent problem in economics is that small interventions that turn out to be very effective usually become ineffective when you scale them up. Jason Kerwin has a great blog post about this, called “Nothing Scales”. (2021-11-03-KerwinNothingScales)

[W]e rarely actually run the original intervention at larger scale. Instead, the tendency is to water it down, which can make things significantly less effective.

Universal pre-K, of the type Joe Biden would create, is the most scaled-up program of all.

But maybe that’s OK, because even at large scales, pre-K has another big benefit: It’s a form of day care.

do more than just teach kids stuff; they also take the kids off of their parents’ hands.

Taking care of kids at home requires a massive about of (unpaid) labor. And it’s very inefficient labor, too — schools have economies of scale, where each teacher supervises a dozen or more kids. An advanced economy is based on specialization

Gains in parental income are an important component of the returns to [pre-K programs] because the program provided care for up to nine hours a day, thus enabling mothers to increase their labor supply. Early childhood education has effects not only on the children, but also on the economic lives of their families. It is a form of enriched childcare that enables mothers to work

In fact, it’s even possible that increased family income is a major reason that pre-K programs have the positive long-term effects that they do have!

when you give poor people day care, their kids tend to benefit relative to their alternatives

when you force rich parents to send their kids to day care, maybe they just get hurt relative to their own alternative.

The right thing to do seems to be to make pre-K free but not universal.

Giving every parent the option of enrolling their kids in a free, government-run pre-K program (i.e., day care center) sounds like a pretty good idea.