Sunday, April 16, 2006

Public schools are better than private schools

Wow. This is HUGE, and no one seems to have noticed it. Back in May 2005, Sarah Theule Lubienski and Christopher Lubienski published a report in the Phi Delta Kappan saying that after controlling for student background, mathematics achievement in public schools is actualy higher than that in private schools. It's a striking finding: as the authors note,

The study focused solely on student achievement in mathematics -- a subject generally thought to be less influenced by family background and more influenced by institutional effects than other school subjects such as literacy.

In other words, if this is true for mathematics, it's likely to be even more true for other subjects.

The study went all but unnoticed: Google shows the grand total of four web pages linking to it. I only found it because one year later, the Atlantic found 127 words for it in its "Primary Sources" column.

This is a question I've been interested in for a while. In fact, last year, when I was reviewing Freakonomics, I put the question to Steven Levitt in an email:

I'm interested in the practical implications of your parenting chapter. It's long struck me that private primary and secondary education is probably the single most expensive thing in America which nobody ever seems to stop and wonder whether or not it's worth it. I've seen lots of citations of the value of a college education, but I've seen nothing about the marginal value of a private-school education over a public-school education, or even whether it's nonzero. Do you think this is something which private schools can or should be able to provide? Data showing that, after adjusting for parents' income etc etc, privately-educated kids do measurably better than they would have done in their local public schools?

Levitt replied:

Absolutely fantastic question. It is something I have been interested in myself, but haven't done research. It is a tough question, but the best research I have seen suggests that Catholic schools might provide benefits to inner-city black children. I am not aware of any evidence on college prep type of private schools like the one I went to, but it may be out there. My own research, which we touch on in the book, suggests that peer effects are much less important than people tend to think -- folks aren't good at separating inputs from outputs. Which is your point I think. The biggest peer effects we see in my work is on outcomes like going to jail, but almost nothing on test scores or graduation.

Well, now we have some data, and it seems to show that paying for a private-school education is money very badly spent: it's like shelling out for a mediocre car when the government will give you a better one for free.

Here are the graphs showing private-school and public-school achievement in fourth grade and eighth grade, within SES (social-economic status) quartiles:

In all four quartiles in both grades, public-school kids clearly outperform their private-school counterparts. Although private schools do have better mathermatics results than public schools, that's entirely because the kids in those schools are more privileged.

The Lubienskis conclude:

Our findings suggest that it is time for a critical reexamination of common assumptions regarding the effectiveness of public and private schools. As market-style reforms change the public school landscape, prompting many to call for various forms of privatization of schooling options, it is important to examine the evidence regarding whether private schools are, indeed, more effective than public schools. In our study, once we accounted for the fact that private schools tend to have higher-SES students than public schools, we actually found just the opposite of what was expected: public schools outperformed private schools within each SES quartile.

I could put it more simply: send your kids to public school. They'll do better than they would at private school, and with the money you save you can further improve their upbringing, education and lifestyle in many other ways.

UPDATE: It turns out there's a more extensive and later survey, with much the same conclusions, which can be found here and was reported on in the NYT here.

Posted by Felix at 18:41 EST

Comments

Um, where is the correlation between test scores and performance later in life (I guess income would be the best metric, or adult SES)?

I thought it was generally assumed that investment in private schools wasn't to actually make your child smarter, but simply to increase the odds of them gaining admission to selective institutions further up the chain to that show correlations to higher income in adults.

It's a fairly easy argument to make that intergenerational wealth transfer generally falls a path of degredation (that is, those inheriting wealth tend not to generate much additional wealth beyond the institutional effects of trusts and investments), so educating the childern of elites isn't about egalitarian performance, but insulating them from those very market forces you are talking about.

Maybe your east coast perspective is inhibiting an understanding of private education nationwide. Outside of the northeast (and really, given enrollment, it's not like Horace Mann or Groton even register as statisical blibs), private eduaction primarily means catholic education, and there is the admitted correlation between catholic education for inner city students and higher scores.

I think your general point is admirable, but the data could also be used to justify not giving NYC the additional funds mandated by the state, and that doesn't seem to be the end you have in mind.

Posted by: 99 at 20:20 EST, April 17, 2006

Even controlling for SES, there are important geographic differences to consider. Within a high-SES group, the marginal value of private education for residents of a wealthy suburb is much less than the marginal value of private education for wealthy residents of a large city such as NYC, I'd imagine.

Posted by: vj at 22:38 EST, April 17, 2006

Well, this is interesting. But does it mean that the money spent on private schools is wasted? I don't think so. It's the promise of status gain that really leads people to send their kids to private school. Having attended private school gives you access to further status resources, and *that's* what you pay the money for.

Posted by: Ben at 4:12 EST, April 18, 2006

Trying to figure out why this study hasn't received more attention than it has, perhaps the reason is that its findings may have actually always been seen as true -- until only relatively recently. That is, perhaps the results are "surprising" only when looked at in the light of relatively "recent" (post-1970s school "reforms" and white flight, etc.) American history. And while the pre-1970s aren't all that recent anymore, they are recent enough for many educators and policy analysts to have a first-hand recollection/knowledge of them.

One immediate illustration that comes to mind:

Although the study chose not to include high school students (for good reasons), when one looks at the winners of the prestigious mathematical and science prizes for high school students (e.g., the Intel Awards, originally called the Westinghouse Awards), it seems to me that the winners are usually from public high schools -- at least that has been the case in the NYC area (e.g., Stuyvesant High School, Bronx High School of Science, etc.) which seems to usually garner the largest percentage of winners year after year (at least from the 1960s onward).

Another illustration:

When I was a student in the NYC school system in the 1950s and 1960s, I think most people assumed (correctly or incorrectly) that NYC public schools were both the best (usually) and the worst (occassionally) and that education at private schools was usually just on par, or even sometimes "second rate," when compared to the vast majority of NYC public schools (i.e., those not in "bad" neighborhoods) -- with the kids in parochial schools being sent there for religious or disciplinary reasons and the kids in prep schools being put there for social or disciplinary reasons.

Posted by: Benjamin Hemric at 18:21 EST, April 18, 2006

save this in my email...

Posted by: mustapha at 10:44 EST, June 25, 2006

This debate over public schools and private high schools will never end. Both types of schools are working hard to provide a good and high standard education to students and both are good.

Posted by: Public vs Private High Schools at 2:38 EST, May 13, 2008