A large-scale government-financed study has concluded that students in regular public schools do as well or significantly better in math than comparable students in private schools.

The study, by Christopher Lubianski and Sarah Theule Lubianski of the University of Illinois, compared fourth- and eighth-grade math scores of more than 340,000 students in 13,000 regular public, charter and private schools on the 2003 National Assessment of Educational Progress. The 2003 test was given to 10 times more students than any previous test, providing a trove of data.

Though private school students long have scored higher on the national assessment, commonly referred to as "the nation's report card," the new study used advanced statistical techniques to adjust for the effects of income, school and home circumstances. The researchers compared math scores because, they said, math is considered a clearer measure of a school's effectiveness.

The study found that while the raw scores of fourth-graders in Catholic schools, for example, were 14.3 points higher than those in public schools, when adjustments were made for student backgrounds, those in Catholic schools scored 3.4 points lower than those in public schools. A spokeswoman for the National Catholic Education Association did not respond to requests for comment.

The exam is scored on a 0-500 point scale, with 235 being the average score at fourth grade, and 278 being the average score at eighth grade. A 10-11 point difference in scores is roughly equivalent to one grade level.

It also found that charter schools, privately operated and publicly financed, did significantly more poorly than public schools in the fourth grade, once student populations were taken into account. In the eighth grade, students in charters did slightly better than those in public schools, though the sample size was small and the difference was not statistically significant, the study said.

"Overall," the study said, "demographic differences between students in public and private schools more than account for the relatively high raw scores of private schools. Indeed, after controlling for these differences, the presumably advantageous private school effect disappears, and even reverses in most cases."

The findings are likely to bolster critics of policies supporting charter schools and vouchers as the solution for failing public schools.

Under President Bush's signature No Child Left Behind law, children in poorly performing schools can switch schools if space is available, and in Washington, D.C., they may receive federally financed vouchers to attend private schools.

Howard Nelson, a lead researcher at the American Federation of Teachers, said the new study is based on the most current and comprehensive national data available. The AFT, an opponent of vouchers that has criticized the charter movement, in 2004 studied some of the same data and reported that charter schools lagged traditional public schools.

"Right now the studies seem to show that charter schools do no better, and private schools do worse," he said. "If private schools are going to get funding, they need to be held accountable for the results."

Supporters of vouchers and charter schools, however, pointed to the study's limitations, saying it gave only a snapshot of performance, not a sense of how students progress over time. Jeanne Allen, president of the Center for Education Reform, said other state and local studies showed results more favorable to charter schools.

Nelson Smith, president of the National Alliance for Public Charter Schools, said many students come to charter schools after doing poorly in traditional public school, and take time to show improvement. "Snapshots are always going to be affected by that lag," Smith said.

Officials at the U.S. Education Department, which has been a forceful proponent of vouchers and charter schools, said they did not see this study as decisive. "We've seen reports on both sides of this issue," said Holly Kuzmich, deputy assistant secretary for policy. "It just adds one more to the list."

The study was financed with a grant from the Education Department's Institute of Education Sciences, but was independent. The federal government is expected itself to issue two more studies looking at the same data and using similar techniques. Those studies are still undergoing peer review, but are expected to be released in early spring.

The study found that self-described conservative Christian schools, the fastest growing sector of private schools, fared poorest, with their students falling as much as one year behind counterparts in public schools, once socioeconomic factors such as income, ethnicity and access to books and computers , were considered.

Taylor Smith, a vice president at the Association of Christian Schools, which represents 5,400 conservative Christian schools, said many members did not participate in the national assessment, which he thought could make it a skewed sample. He didn't know how many schools from other Christian groups participated.

The report found that among the private schools, Lutheran schools did better than other private schools. Nevertheless, at the fourth-grade level, a 10.7 point lead in math scores evaporated into a 4.2 point lag behind public schools. At the eighth-grade level, a 21 point lead, roughly the equivalent of two grade levels, disappeared after adjusting for differences in student backgrounds.

Copyright New York Times BY DIANA JEAN SCHEMO

The crumbling neighborhood public school down the block or that gilded private school on a hill? There's a tendency to imagine the two this way - and to assume the private school will produce better students.

But beleaguered public schools have recently received a small, though noteworthy, boost. After accounting for students' socioeconomic background, a new study shows public school children outperforming their private school peers on a federal math exam.

Overall, private school students tend to do markedly better on standardized tests. But the reason, this study suggests, may be that they draw students from wealthier and more educated families, rather than because they're better at bolstering student achievement.

One study is unlikely to settle a long-simmering debate over the merits of public versus private education. But its authors say they hope it will give pause to a current trend in education reform: privatization.

From tax-dollar financed vouchers for private schools to a drive to put public schools in private hands, market-style reforms are all the buzz in education.

Competition, the reasoning goes, is healthy for schools. Those that must produce results to survive have to be better than those that don't face such pressure.

But these findings "really call into question the assumption of some of the more prominent reform efforts," says Christopher Lubienski, an education professor at the University of Illinois at Urbana-Champaign, who wrote the study with his wife Sarah Theule Lubienski, also an education professor at the university.

In particular, says Mr. Lubienski, it challenges the assumption that "the private-school model is better and more effective, and can achieve superior results. It really undercuts a lot of those choice-based reforms."

"A New Look at Public and Private Schools: Student Background and Mathematics Achievement" appears in the May issue of Phi Delta Kappan, a highly regarded education journal.

Analyzing raw data from the 2000 National Assessment of Educational Progress for 28,000 fourth- and eighth-graders representing more than 1,300 public and private schools, Mrs. Lubienski, whose research focuses on equity issues in math education, was surprised by what she was seeing. When children of similar socioeconomic status were compared, the public school children scored higher. She called in her husband, who studies school choice and privatization, to help interpret the results.

At most, a small difference

When the students were divided into four socioeconomic groups, the difference between public and private school math scores was 6 to 7 points for fourth-graders in each group, and 1 to 9 points for eighth-graders. Not a large difference, says Mrs. Lubienski - more "small to moderate."

The crux of the study isn't so much to suggest that public schools are outpacing private schools as to call into question a common assumption: "It's more: 'Wow, this flies in the face of what we thought - that private schools do better than public.' "

Some, however, are skeptical. Any time studies produce "counterintuitive" results, they should be carefully examined, says Joe McTighe, executive director of the Council for American Private Education (CAPE).

Without having seen the Lubienskis' research, he points out that raw scores have typically shown the country's 6 million private school students, who make up 11.5% of US schoolchildren, outperforming public school students.

But others say the results are not that surprising.

"We would conclude, on the basis of perhaps 15 years of research, that there's nothing magic about privatization," says Henry Levin, a professor of economics and education at Columbia University's Teachers College in New York, and director of the National Center for the Study of Privatization in Education.

The 'peer effect'

For the most part, he says, the academic benefits of attending a public or a private school have been relatively small, when compared in studies.

Certainly the stubborn gap between the academic achievement of white and minority students across the board is greater than the gap between public and private school performances.

That's a salient point for those who oppose the idea of privatization as a cure for the ills of US public education. Unless private schools have a measurably better track record than public schools, it's hard to argue that privatizing education will necessarily boost performance for all students.

"The bigger picture here," says Professor Levin, "and I don't care which good study you look at - the [differences in public and private school] results are tiny."

By way of example, Levin cites a comprehensive 2002 study that examined public and private schools in Latin America.

There, raw test scores favored private schools. But once student socioeconomic status was taken into account, that advantage shrank - as the Lubienskis had found. After the study factored in what is called "peer effect" - the influence of other students and school environment - the overall difference across 10 countries was zero; achievement at public and private schools was equal.

In the end, says Levin, ideology often trumps research and drives the debate, with proponents on either side highlighting only data that support their case.

Parents opt for intangibles

Chances are, the Lubienskis' study won't have much impact on the choices that parents make.

"When parents make decisions about schools," says Mr. McTighe of CAPE, "they don't compare these constructed statistical abstracts. They look at a particular school in a particular neighborhood and ask: Is that school the right match for my child?"

Often, intangibles - a safe environment and caring staff or a culture that embraces and reflects a family's values - influence the decision as much as test scores.

And public opinion about the quality of schools is nuanced.

According to a 1999 Public Agenda poll, 52% of parents said private schools generally provide a better education. Only 19% thought a public education was better.

Yet many parents still hold public schools in high regard. The annual Phi Delta Kappa/ Gallup Poll of the Public's Attitude Toward the Public Schools has, since 1983, consistently reported parents giving public schools high marks - in the "A" and "B" range. The closer a parent is to the school, the better the grade.

If nothing else, the Lubienskis' findings are "a nice thing for the public schools to hear," says Kathy Christie of the nonpartisan Education Commission of the States in Denver. "It's most validating in that way."

USA Today / Christian Science Monitor Copyright © 2005 By Teresa Méndez,