This is the Cato Daily Podcast for Tuesday, October 27th, 2015.

I'm Caleb Brown.

The evidence for pre-K education hasn't changed much over recent years.

A new study by researchers at Vanderbilt has found, again,

that the benefits of pre-kindergarten education

fade after a few years.

Neil McCluskey, director of the Cato Institute's

Center for Educational Freedom, discusses the findings.

What do we already know about preschool for young children and what that what the payoff is.

Well there's a lot we don't seem to know about preschool.

What we have is basically if you look at the research and entirety we have is, basically if you look at the research in entirety, we have two studies of very

small, very intensive programs from the 1960s and early 1970s that seemed to show there is some lasting benefit

for pre-kindergarten. But you've got to understand when I say small each one had a treatment size of about 57 kids and they were extremely intensive so they involved home visits they were run by the people who are trying to prove that their model

worked as opposed to just people who run pre-K centers. And so those are not at all analogous to what people are trying to get now, which is a universal pre-kindergarten, to some extent.

So some places will say, well, let's get all low-income five-year-olds, let's get, some will say let's get all low-income five-year-olds let's get

some will say let's get all five-year-olds say let's get all low-income four and

five-year-olds or or three and four-year-olds rather but the drive is to have more and more kids in these programs.

And so there have been studies of these more modern programs,

but the large majority suffer from big methodological problems as actually David

Armour talked about in a Cato paper came out about a year or so ago. They don't

have random assignment studies. They use either regression discontinuity designs or other kinds of studies that don't allow you to especially control for the motivation of parents who are involved. These regression discontinuity

designs, you can't actually follow the progression of kids who had pre-K versus those who don't.

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