Apples and Oranges: Comparing Private and Public School Test Scores

Ever wished you could compare private and public schools somehow? Perhaps with test score data?

By Marian Wilde , GreatSchools Staff

Unfortunately, comparing private to public school test scores is a bit like comparing apples to oranges.

Public schools use their own stable of standardized tests, which they use for a variety of purposes: assessment and diagnostics, to name two. Private schools use a different set of tests - some derived from the same basic tests public schools use and created by the same companies - but still different enough that they can't be compared side by side with public school tests.

Public schools are required by law to administer the test chosen by the state government and to publish their test scores. Meanwhile, private schools are free to pick their own standardized tests and, because they don't rely on public funds, do not have to release their scores, though interested parents can ask to see them.

A parent in research mode cannot even compare public schools across state lines because of the wide variety of tests in use nationwide. In order to do that, all public schools would have to administer the same exam. Currently, only schools in a given state do that.

For better or worse, standardized testing seems to be here to stay. The question now is how to use test score data wisely. With that goal in mind, a handful of education researchers and school officials are working to achieve greater transparency and accountability for all types of schools.

One Way to Compare: NAEP

Several recent large-scale studies have compared private schools to charter and regular public schools using the one common test taken by selected samples of students around the country.

That test is the National Assessment of Educational Progress (NAEP), otherwise known as the Nation's Report Card. Administered by the U.S. Department of Education, the NAEP is given to students in grades 4, 8 and 12 in both private and public schools.

One of these studies, conducted by Christopher and Sarah Theule Lubienski, a husband-and-wife team at the University of Illinois, compared more than 340,000 students using math scores from the 2003 NAEP. The study found that after adjusting for socioeconomic factors, there is little difference between private and public school scores. According to the researchers, "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."

Similarly, another study - Comparing Private Schools and Public Schools Using Hierarchical Linear Modeling - used the 2003 NEAP data. It found that after adjusting for student characteristics such as gender, race, ethnicity, disability status and English-language proficiency and for school characteristics such as size, location and the makeup of the student body, the fourth-grade reading test scores were virtually the same for private and public schools, although the math scores for public schools were higher. In eighth grade, private school students performed better in reading, but there was virtually no difference in math.

Why Most Private Schools Don't Publish Test Scores

Public schools are required by state and federal regulations to publish their test scores, but private schools - operating without public funds and outside of close government supervision - are not obligated to do so.

Just as in the public school arena, the private school community debates how much emphasis to place on test scores. Many private schools pride themselves on providing creative and nurturing environments rather than a one-size-fits-all education. Patrick F. Bassett, president of the National Association of Independent Schools, writes on the NAIS Web site that, "those who understand curriculum and instruction, and who are rightfully skeptical about the value of standardized tests in general, also worry very much about the deleterious impact of the movement on children. With all the memorization and test preparation, will students still be taught to think critically? Will they learn to love learning?"

Others argue that private schools should report how well they are doing to the community. Henry Tyson, superintendent of St. Marcus Lutheran School in Milwaukee, believes that publishing private school scores will help parents make informed decisions when choosing schools. "The reality is that there is very little accessible, useful information that parents can use," says Tyson. "The critical problem right now is that thousands of parents [in Milwaukee] are choosing very bad schools for lack of good information."

Tyson acknowledges that releasing isolated test scores can be problematic. "Test scores must be publicized in a way that makes sense - the data needs to communicate value added by the school and be supported by other information like attendance rates, graduation rates and expulsion rates," he explains.

Will Private Schools Ever Publicize Their Scores?

Tyson is currently in discussions with other private school principals in Milwaukee about the possibility of publishing their scores. "The problem is that it's hard to reach agreement about what information should be reported," says Tyson. "Sadly, some schools, public and private, make the discussion more complicated than it needs to be simply because they don't want to report any information, because they are not performing and they know it."

Meanwhile, trends toward more data collection and analysis, making information available to the public and using test scores to compare and evaluate schools continue to gather strength in the public sector, nationally and internationally. This no doubt will eventually impact private schools around the nation.