Insight
The private school advantage? Maybe not
Feb 16, 2006 2:44 PM
Comparing private schools and public schools is risky business. It’s not only “apples to oranges” in terms of the cost, or the type of governance. In many cases, it’s apples to grapefruits in terms of the children and families each system serves and the missions of the schools themselves.
That hasn’t stopped voucher advocates from arguing that poor children should get public funds to attend private schools. They just assume the privates do better; they create a sort of mystique around private-school education. And in many New York City neighborhoods, it’s commonly believed the Catholic schools are a better option than the public schools because children will score higher on standardized tests if they attend them.
Gov. George Pataki, buying into this version of the truth, proposes giving parents a tax credit of $500 to spend on private tutoring or private schooling. (That would cost the state $400 million a year, the governor estimated in his new budget proposal.)
Think again
But the “fact” that private-school students consistently outscore their public-school counterparts on standardized tests has just been re-examined and found to be, well, not so factual.
The new report, by Teachers College’s National Center for the Study of Privatization in Education and funded by the U.S. Department of Education, finds that, after fully controlling for demographic differences between students in public and private schools, the presumed advantages of private schools disappear; in fact, in most cases public schools outperform private schools, on an apples-to-apples basis (see chart).
The study also examined the math performance of students in charter schools, and again, found that charter schools do no better — and perhaps worse — than regular public schools.
A few years ago, there were studies finding just the opposite. But recently their findings have been called into question, and voucher and charter advocates have stopped referring to them.
The authors of this new report, Christopher Lubienski and Sarah Theule Lubienski of the University of Illinois, used 4th- and 8th-grade math scores from the 2003 National Assessment of Education Progress (NAEP) to compare school types. (They chose math because it is “a subject that is learned primarily in school,” versus reading, which is more influenced by students’ experiences at home.)
Using “raw” or unadjusted scores alone, students in private and charter schools did outperform regular public schools. But once the researchers adjusted the scores for the factors associated with student differences — socio-economic status, race, students with limited English proficiency, numbers of special education students in each group, counts of books in the home, and school location (urban, rural, suburban) — the comparison flipped. In other words, if the private-school students had higher scores it was because of the characteristics they brought to school, not what the school did for them.
A ‘presumed panacea’
For example, the raw score of the average Catholic-school 4th-grader was 9.5 points higher than the public-school average; but once adjusted, the Catholic-school lead morphs into a deficit: Catholic-school children score 7.2 points lower. The same holds true across the board: all things equal, the regular public schools outperformed Catholic, Lutheran, conservative Christian and other independent schools, as well as charter schools, in 4th grade and in most cases in 8th grade as well.
“The presumed panacea of private-style organizational models — the private-school advantage — is not supported by this comprehensive dataset on mathematics achievement,” the Lubienskis write. “These data suggest significant reasons to be suspicious of claims of general failure in the public schools, and raise substantial questions regarding a basic premise of the current generation of school reforms based on mechanisms such as choice and competition drawn from the private sector.”
This study had the advantage of an exceptionally large pool — 190,000 4th-graders and 153,000 8th-graders, 10 times the size of the previous NAEP. But most important, the Lubienskis skillfully controlled for a multiplicity of factors, not just free-lunch eligibility. Any teacher can tell you that income is not the only difference between poor and middle-class children, and previous studies have stopped short of including the full range of differences, from percentage of English language learners to computers at home.
The new study has drawn heat, of course. Researchers who have found positive charter school effects, such as Caroline Hoxby, maligned its statistical techniques. The conservative, pro-voucher Thomas Fordham Foundation professed boredom. “You may be asking yourself: Isn’t this the 147th study to examine the performance of public, private, and charter school students on the 2003 National Assessment of Educational Progress?” begins the coverage in its newsletter. Indeed, economists and policy analysts who believe the “market” is the best driver of school improvement, and who are committed to school choice as a remedy, probably will not be persuaded no matter what the data show.
Fixing what isn’t broken
Of course, some private schools are phenomenal. And some are absolutely terrible. The same goes for charter schools and for public schools. The Lubienskis are plotting averages, while schools in each sector vary widely. In some ways the comparisons are odious. We Americans treasure our diversity, which is why such practices as a national curriculum are far from mainstream thinking. Most people would be happy to see schools of all stripes flourish.
But it is important to carefully evaluate the claims and assumptions of anyone with a recipe to “fix” the schools. There is nothing mystical in the private sector that makes private schools better. In fact, New York State public school teachers are on average more experienced, have higher levels of education and are far more likely to be certified than teachers in the state’s private schools. Charter-school operators often lack any educational experience at all.
So before the governor sends $400 million of taxpayer money to private schools, or the charter school cap is raised, or the courts allow vouchers, citizens should get to see exactly what they’ll be buying: not the mystique, but the reality. That gets into accountability, a subject for a whole other column, to come.
The Lubienski study is quite readable: Find it online in PDF format.
