Public school students do better on NAEP math tests than private school students with similar family and student characteristics, according to a new authoritative study posted on the Web site of the Center for the Study of Privatization at Columbia University.

The authors, Sarah Theule Lubienski and Christopher Lubienski, both affiliated with the University of Illinois, expected to find that private school students score better. But instead, their findings refute the myth that students will learn better if they are sent, through vouchers or other means, to private schools.

Among the unequivocal results showing the voucher dream is a pipe dream:

• Mean scores of public school 4th graders are 6-7 points higher than those of private school 4th graders within each socioeconomic status (SES) quartile. (A NAEP point is considered to be roughly equivalent to a month of schooling.)

• In grade 8, public school students outscore Catholic school students by an average of 6.5 points and other private school students by 3.7 points when race, SES and disability are considered. Both findings are statistically significant.

No one doubts that many public schools need to do more to help children learn. But this study offers at least two caveats for would-be education reformers and those in reporters on the education beat.

First, be skeptical of the voucher blob (see side panel for definition), which claims that sending students to private schools is a panacea for what ails public education.

Second, beware of studies that ignore out-of-school factors when evaluating and comparing schools. This commonsense observation has been made by thinkers as diverse as Chester E. Finn, Jr., and Richard Rothstein, and it is especially relevant in comparisons of private schools. As the authors note, more than 80 percent of private school students are advantaged, compared to fewer than 40 percent of public schools.

The authors, going where the facts led them and ignoring their own expectations, discovered something that bears repeating: Public school students do better than similar private school students on NAEP math tests.

May 15, 2005