But more recently, when she was working on a study of math instruction, Sarah Lubienski came across a result she didn’t expect. When she divided the schools she was looking at into public and private categories and controlled for demographics, the schools stacked up quite differently. Public schools seemed to be producing better test scores than private. They were also doing better than charter schools.

Like many in their field, Christopher and Sarah Lubienski, education professors at the University of Illinois, had long taken it as a given that private schools generally outperform public schools. Why would parents shell out thousands of dollars a year in tuition if they weren’t getting more for their money? Moreover, studies in the 1980s and ’90s had apparently settled the matter, showing that private schools produced higher test scores even when accounting for the demographic differences between public and private.

“That,” says her husband and colleague Christopher Lubienski, “is when we started investigating this more intensively.”

They decided to take a new, in-depth look at nationwide standardized test data. Using results from the math portion of the National Assessment of Educational Progress, or NAEP, the Lubienskis compared scores from more than 13,000 public, private and charter schools. The private schools did have higher raw scores. But once they controlled for factors like family income, race, and location, they found that public schools were overall getting better results from their students.

The Lubienskis locate the reason in a surprising place: private-school autonomy. School reform advocates have long argued that more autonomy would allow public schools to innovate, and that letting families choose where to send their kids would force schools to improve their game. But the Lubienskis argue that independence and competition may actually be holding back achievement at private and charter schools. In a new book, “The Public School Advantage: Why Public Schools Outperform Private Schools,” they outline their findings and walk through the implications. The result may lead education reform advocates to rethink their policies—and parents to question one of their most important decisions.


Christopher Lubienski spoke to Ideas by phone from his office in Champaign, Ill.

IDEAS: The thought of a “public school advantage” seems counterintuitive, and as you mention in the book it was initially a surprise to you, too. What did the data show?


LUBIENSKI: We know that private school students tend to score higher than students in public schools. But we also know that these are different populations, and they have different selection criteria. So we looked at the demographics of the different students in these nationally representative data sets, and we found those demographics more than explain the student achievement patterns....We focused specifically on mathematics, because math achievement is a better reflection of the school effects rather than the other subjects, like reading, which are often reflective of what the students are learning at home....Once we actually delved into those achievement statistics, public schools turned out to be more effective. Public school students are outscoring their demographic counterparts in private schools...at a level that is comparable to a few weeks to several months.

Christopher Lubienski and his research partner and wife, Sarah. Anna Katherine Lubienski

IDEAS: So public school students might be months ahead of their peers. And what about charter schools?

LUBIENSKI: They were already scoring beneath public schools before you control for demographics....But even once you control for those demographics, charter schools were still performing at a level lower than public schools, by as much as several months.

IDEAS: What’s going on there? That’s the opposite of what most people would probably expect.

LUBIENSKI: Most people would say [charter schools are better] because they are not bound by all the rules and regulations that public schools are run by. But our research shows that autonomy can be a problem for independent schools, including charter schools. You would think that having that autonomy would be an opportunity to experiment with new and more effective pedagogical or curriculum approaches, for example, and I’m sure that happens in some cases. But what we found was many of these types of schools are actually using their autonomy to embrace outmoded or outdated curricular or instructional functions. What we think is happening is that...when they are faced with competitive pressures, they have to compete with other schools for students, so they often adopt a culture that parents feel is tried and true, and what they experienced when they were at school.


IDEAS: So the good old “three R’s” aren’t what they’re cracked up to be?

LUBIENSKI: A lot of public schools have embraced more state-of-the art approaches that have been really influenced and shaped by experts in the field; for example, the National Council of Teachers of Mathematics has recommended certain curricular approaches that reflect what we know about how students learn. It’s really apparent when you look at the teaching and the curriculum in the different types of classrooms. The other thing is that public schools have to work under some [legal] requirements, and one of those is they have to hire certified teachers. Teacher certification does make a difference. It’s a good predictor of student achievement.

IDEAS: But unlike your neighborhood public school, private schools have to compete to get parents to send their kids there.

LUBIENSKI: What we’re seeing is as competition increases in these areas, schools often take on strategies that might not always mean the best outcomes for students. A lot of them are taking resources out of the classroom and putting them more into things like marketing....Actually, schools are making some choices that are quite questionable.


IDEAS: So are parents wasting their money when they send their kids to private school?

LUBIENSKI: Parents aren’t always choosing the most effective schools, but they have other things that are often more of a priority....I’m not going to say any reason is good or bad, but there are reasons like proximity, safety. [Parents] look at the demographic makeup of the school to see if it is something their children will fit into. Putting a child in a wealthier school in a wealthier climate has an advantage called the peer effect—if your child is sitting at a lunch table with other kids who are talking about how they are going to complete their homework or what college they are going to go to, that can have a beneficial effect.

IDEAS: What school their children should attend is a difficult decision for many families. How can they take your findings into account?

LUBIENSKI: I think what this suggests is that it makes sense to put aside preconceived notions about one type of school necessarily being better than another, and then ask questions about things like are we dealing with qualified teachers?...But this is nationally representative data, so I would think these figures would speak more to our policy makers.

IDEAS: How should your study inform education policy?


LUBIENSKI: For several years, there has been this bipartisan push for education reform—from the Bush administration, Obama, the Clinton administration—all with the same ideas....One of the main assumptions is that if you further deregulate, adopt a private-style method for schools, that it might be more effective and lead to higher academic outcomes....When you start to look at the data, the evidence doesn’t necessarily bear that out.

Amy Crawford has written for Boston Magazine, Smithsonian, and Slate. Follow her on Twitter @amymcrawf.