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Andrew Maul, (303) 492-7653,
Dan Quinn, (517) 203-2940,

Sound CREDO Michigan Charter School Report Provides Little Basis for Advocacy

EAST LANSING, Mich. (Feb. 12, 2013) – The overall research base is now clear that the charter school sector largely mirrors the conventional public school sector in terms of students' test scores. This is again confirmed by a recent analysis of charter schools in Michigan. A new review of that study points to some limitations but concludes that it employs solid analytic methods and relies on a large, impressive dataset.

The Michigan report is the work of the Center for Research on Education Outcomes (CREDO) at Stanford University. The CREDO researchers analyzed differences in student performance at charter schools and traditional public schools in Michigan.

Andrew Maul of the University of Colorado Boulder reviewed Charter School Performance in Michigan. The review was produced by the National Education Policy Center with funding from the Great Lakes Center for Education Research and Practice.

Up to this point, the majority of high-quality research studies on charter effects in the U.S. have tended to show no meaningful impact—positive or negative—on student achievement. Against this background, charter advocates have trumpeted the new CREDO Michigan study as a "smashing success" for charter schools.

In truth, the new study estimates that students in charter schools in Michigan experience 0.06 standard deviations more academic growth than comparison students in traditional public schools. As Maul points out, "This is equivalent to saying that about a tenth of one percent of the variation in academic growth is associated with school type." Such a finding of almost no difference between charters and non-charters is very much in line with the overall body of past research. Some studies suggest slight benefits, some suggest slight harm, and many show no difference.

The study itself has both strong and weak elements. "As with CREDO's previous reports on charter schools, the study employs a large and comprehensive dataset and fairly solid analytic methods," Maul notes. But he goes on to point out "significant reasons for caution in interpreting the study's results."

Maul's discussion of research methods is somewhat technical but is clearly explained in his review. One concern is the study's failure to use methods that could have directly modeled both individual student growth and school-level effects, such as hierarchical linear modeling, which would have been better matched to the goals of making generalizable statements about both students and schools. He also questions whether the seven variables used in the study's "virtual twin" matching approach are truly sufficient to capture all meaningful differences between charter students and those at traditional public schools.

Despite such caveats, Maul concludes that the study contains enough information that it represents an interesting contribution to the research literature on charter school effectiveness.

Find the Think Twice Review on the Great Lakes Center website:

Find Charter School Performance in Michigan, the web:

Think Twice, a project of the National Education Policy Center, provides the public, policymakers and the press with timely, academically sound reviews of selected publications. The project is made possible by funding from the Great Lakes Center for Education Research and Practice.

Find Andrew Maul's review on the NEPC website at:


The mission of the Great Lakes Center for Education Research and Practice is to support and disseminate high quality research and reviews of research for the purpose of informing education policy and to develop research-based resources for use by those who advocate for education reform.

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