(New York Times, Saturday, July 15, 2006.)

By Diana Jean Schemo

WASHINGTON, July 14 - The Education Department reported on Friday that children in public schools generally performed as well or better in reading and mathematics than comparable children in private schools. The exception was in eighth-grade reading, where the private school counterparts fared better.

The report, which compared fourth- and eighth-grade reading and math scores in 2003 from nearly 7,000 public schools and more than 530 private schools, found that fourth graders attending public school did significantly better in math than comparable fourth graders in private schools. Additionally, it found that students in conservative Christian schools lagged significantly behind their counterparts in public schools on eighth-grade math.

The study, carrying the imprimatur of the National Center for Education Statistics, part of the Education Department, was contracted to the Educational Testing Service and delivered to the department last year.

It went through a lengthy peer review and includes an extended section of caveats about its limitations and calling such a comparison of public and private schools "of modest utility."

Its release, on a summer Friday, was made without a news conference or comment from Education Secretary Margaret Spellings.

Reg Weaver, president of the National Education Association, the union for millions of teachers, said the findings showed that public schools were "doing an outstanding job" and that if the results had been favorable to private schools, "there would have been press conferences and glowing statements about private schools."

"The administration has been giving public schools a beating since the beginning" to advance its political agenda, Mr. Weaver said, of promoting charter schools and taxpayer-financed vouchers for private schools as alternatives to failing traditional public schools.

A spokesman for the Education Department, Chad Colby, offered no praise for public schools and said he did not expect the findings to influence policy. Mr. Colby emphasized the caveat, "An overall comparison of the two types of schools is of modest utility."

"We're not just for public schools or private schools,'' he said. "We're for good schools."

The report mirrors and expands on similar findings this year by Christopher and Sarah Theule Lubienski, a husband-and-wife team at the University of Illinois who examined just math scores. The new study looked at reading scores, too.

The study, along with one of charter schools, was commissioned by the former head of the national Center for Education Statistics, Robert Lerner, an appointee of President Bush, at a time preliminary data suggested that charter schools, which are given public money but are run by private groups, fared no better at educating children than traditional public schools.

Proponents of charter schools had said the data did not take into account the predominance of children in their schools who had already had problems in neighborhood schools.

The two new studies put test scores in context by studying the children's backgrounds and taking into account factors like race, ethnicity, income and parents' educational backgrounds to make the comparisons more meaningful. The extended study of charter schools has not been released.

Findings favorable to private schools would likely have given a lift to administration efforts to offer children in ailing public schools the option of attending private schools.

An Education Department official who insisted on anonymity because of the climate surrounding the report, said researchers were "extra cautious" in reviewing it and were aware of its "political sensitivity."

The official said the warning against drawing unsupported conclusions was expanded somewhat as the report went through in the review.

The report cautions, for example, against concluding that children do better because of the type of school as opposed to unknown factors. It also warns of great variations of performance among private schools, making a blanket comparison of public and private schools "of modest utility." And the scores on which its findings are based reflect only a snapshot of student performance at a point in time and say nothing about individual student progress in different settings.

Arnold Goldstein of the National Center for Education Statistics said that the review was meticulous, but that it was not unusual for the center.

Mr. Goldstein said there was no political pressure to alter the findings.

Students in private schools typically score higher than those in public schools, a finding confirmed in the study. The report then dug deeper to compare students of like racial, economic and social backgrounds. When it did that, the private school advantage disappeared in all areas except eighth-grade reading.

And in math, 4th graders attending public school were nearly half a year ahead of comparable students in private school, according to the report.

The report separated private schools by type and found that among private school students, those in Lutheran schools performed best, while those in conservative Christian schools did worst.

In eighth-grade reading, children in conservative Christian schools scored no better than comparable children in public schools.

In eighth-grade math, children in Lutheran schools scored significantly better than children in public schools, but those in conservative Christian schools fared worse.

Joseph McTighe, executive director of the Council for American Private Education, an umbrella organization that represents 80 percent of private elementary and secondary schools, said the statistical analysis had little to do with parents' choices on educating their children.

"In the real world, private school kids outperform public school kids," Mr. McTighe said. "That's the real world, and the way things actually are."

Two weeks ago, the American Federation of Teachers, on its Web log, predicted that the report would be released on a Friday, suggesting that the Bush administration saw it as "bad news to be buried at the bottom of the news cycle."

The deputy director for administration and policy at the Institute of Education Sciences, Sue Betka, said the report was not released so it would go unnoticed. Ms. Betka said her office typically gave senior officials two weeks' notice before releasing reports. "The report was ready two weeks ago Friday,'' she said, "and so today was the first day, according to longstanding practice, that it could come out."