Charter Schools More Effective with Children Enrolled at Early Age; New Findings in Education Next Raise Doubts over Focus of Federal Study

Tuesday, August 30, 2005

Two studies that shed light on the impact of charter schools on different student populations, published this month in Hoover Institution's Education Next, raise doubts over the focus of a new federal charter school study.

The U.S. Department of Education's "Evaluation of the Impact of Charter School Strategies" focuses on students in middle schools, which constitute only about 20 percent of the country's 3,400 charter schools. This approach runs the risk of obtaining highly skewed results, a point brought to light by the two studies.

Economists Caroline M. Hoxby of Harvard University and Jonah E. Rockoff of the Columbia Business School, in a randomized study of Chicago charter schools, found that charter students in kindergarten through grade 5 outperformed their traditional school peers in reading and math by 2.5 to 3 percentile points for each year they spent in their charter schools.

But a separate study of charter middle school students in North Carolina by Robert Bifulco of the University of Connecticut and Helen F. Ladd of Duke University reveals that students entering charter schools in grades 4 through 8 made smaller achievement gains than they would have had they remained in traditional public schools. In this study, the gap between students in charter schools and students in traditional public schools was an 0.12 standard deviation in reading and an 0.22 standard deviation in math.

The U.S. Department of Education's new five-year study of charter schools, with its focus on middle schools, could well prompt concern, notes Education Next executive editor Marci Kanstoroom. Evaluating charter middle schools enables researchers to use data from tests mandated by NCLB for grades 3 through 8, whereas an effective study of charter elementary schools would require researchers to administer their own tests. Although it is less costly to structure the study in this way, Education Next editor-in-chief Paul E. Peterson points out that "unless we study students who have entered charter schools from the beginning, we will not have an accurate idea of how much value-added these schools are bringing to the educational table."

Read "The Truths about Charter Schools" and "Looking in the Wrong Place" in the new issue of Education Next now online at

Caroline Hoxby is a professor of economics at Harvard University, a member of the Hoover Institution's Koret Task Force on K–12 Education, and the director of the Economics Program at the National Bureau of Economic Research. Jonah E. Rockoff is assistant professor of economics and finance at Columbia Business School.

Robert Bifulco is assistant professor of public policy at the University of Connecticut. Helen F. Ladd is professor of public policy studies and economics at Duke University.

Paul E. Peterson, a senior fellow at the Hoover Institution and a member of the Koret Task Force on K–12 Education, is the editor in chief of Education Next and director of the Program on Education Policy and Governance at Harvard University.

Education Next is a scholarly journal published by the Hoover Institution that is committed to looking at hard facts about school reform. Other sponsoring institutions are the Harvard Program on Education Policy and Governance, the Thomas B. Fordham Foundation, and the Manhattan Institute for Policy Research.