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Review Questions Ostensible Differences between Two Studies Comparing Public and Private Schools

Education Policy Research Unit (EPRU) at ASU
Education and the Public Interest Center (EPIC) at CU-Boulder

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REVIEW QUESTIONS OSTENSIBLE DIFFERENCES BETWEEN TWO STUDIES COMPARING PUBLIC AND PRIVATE SCHOOLS
On closer examination, public and private high schools do about the same

Contact: Jaekyung Lee, (716) 645-2484 (ext 1257); (email) JL224@buffalo.edu
Kevin Welner, (303) 492-8370; (email) kevin.welner@gmail.com

TEMPE, Ariz and BOULDER, Colo. (Dec. 12, 2007) - Two new reports appear to come to different conclusions about whether private schools do better than public ones at promoting student achievement. But a new review of both reports finds little actual difference between their findings - and little difference between the public and private sectors.

The Center on Education Policy (CEP) released one report; the Milton & Rose D. Friedman Foundation (Friedman) released the second. The CEP report was authored by Harold Wenglinsky and entitled, "Are Private High Schools Better Academically than Public High Schools?" The Friedman report was authored by Friedman senior fellow Greg Forster and entitled, "Monopoly Versus Markets: The Empirical Evidence on Private Schools and School Choice." The two reports are similar in that they each use an existing national database and attempt to model the comparative effectiveness of public and private schools at raising test scores.

The two reports were reviewed for the Think Tank Review Project by Jaekyung Lee, associate professor at the State University of New York at Buffalo.

Using the National Education Longitudinal Study (NELS) database, the CEP report presents a statistical model showing no comparative advantage for either public or private schools. The study examined schools serving disadvantaged students in urban settings.

Using the Educational Longitudinal Study (ELS) database, the Friedman report presents a statistical model yielding evidence that private schooling produces a benefit that Lee describes as "very small in absolute terms and its practical significance is questionable." The Friedman report presents its findings in a way that appears to show a larger effect size, by extrapolating from data covering the last two years of high school to impute equivalent gains over 12 years, but Lee points out that the author's underlying assumptions "cannot be reasonably made."

Lee notes that the specific findings of the two studies do not, as a practical matter, greatly differ. Setting aside some concerns he raised regarding each study, Lee explains the small practical significance of the benefits presented in the Friedman analysis. He further explains that even though the CEP analysis shows no overall private school benefits, it does show some that two types of private schools show some positive outcomes: non-religious private high school students obtained higher SAT scores than public school students, and Catholic schools run by holy orders such as the Jesuits had nominal positive academic effects.

Lee also presents his own, independent cross-examination of the two data sources and shows that the public-private high school gaps in math achievement gain scores were almost null (in the NELS) or too small to be practically significant (in the ELS). He concludes that much of the apparent differences between the reports can be accounted for by their use of different datasets, time periods, and target populations, among other things.

In the end, Lee says, while both reports may prompt discussion over the nature of school success and the values underlying school choice, both seem unlikely to adequately guide educational policymakers, practitioners or parents due to their inability to fully account for observed gaps (or the lack thereof) between public and private schools. The most that can be concluded from the two reports taken together is that "students generally learn in public high schools about as well as in private high schools, but ... there are still many unanswered questions about potential differences in the finer details."

Find Jaekyung Lee's review on the web at:
http://epsl.asu.edu/epru/ttreviews/EPSL-0712-246-EPRU.pdf

About the Think Tank Review Project

The Think Tank Review Project (http://thinktankreview.org), a collaborative project of the ASU Education Policy Research Unit (EPRU) and CU-Boulder's Education and the Public Interest Center (EPIC), provides the public, policy makers, and the press with timely, academically sound reviews of selected think tank publications. The project is made possible by funding from the Great Lakes Center for Education Research and Practice.

Kevin Welner, the project co-director, explains that the project is needed because, "despite their garnering of media attention and their influence with many policy makers, reports released by private think tanks can be of very poor quality.  Too many think tank reports are little more than ideological argumentation dressed up as research.  We believe that the media, policy makers, and the public will greatly benefit from having qualified social scientists provide reviews of these documents in a timely fashion."  He adds, "we don't consider our reviews to be the final word, nor is our goal to stop think tanks' contributions to a public dialogue. That dialogue is, in fact, what we value the most. The best ideas come about through rigorous critique and debate."

CONTACT:
Jaekyung Lee, Professor
State University of New York at Buffalo
(716) 645-2484 (ext 1257)
JL224@buffalo.edu

Kevin Welner, Professor and Director
Education and the Public Interest Center
University of Colorado at Boulder
(303) 492-8370
kevin.welner@gmail.com

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The Education Policy Research Unit (EPRU) conducts original research, provides independent analyses of research and policy documents, and facilitates educational innovation. EPRU facilitates the work of leading academic experts in a variety of disciplines to help inform the public debate about education policy issues.

Visit the EPRU website at http://educationanalysis.org

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The Education and the Public Interest Center (EPIC) at the University of Colorado, Boulder seeks to contribute information, analysis, and insight to further democratic deliberation regarding educational policy formation and implementation.

Visit the EPIC website at http://education.colorado.edu/epic

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