Charter School Research: The Beat(ing) Goes On

By Debra Viadero — November 13, 2009 2 min read
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The back-and-forth on charter school research never seems to end.

The latest analysis takes to task the much-publicized study of New York City’s charter schools that was conducted by Stanford University economist Caroline M. Hoxby and colleagues. (You can read more about the original study in this EdWeek article. Read the full text of the Hoxby study here.)

In the new critique, Sean F. Reardon, a colleague of Hoxby’s at Stanford, points up what he sees as flaws in the New York City study. For one, he says, in measuring the effects of charter schooling on students in grades 4-12, the study relies on statistical models that include test scores from the previous year, which are measured after the admissions lotteries take place. Because of that timing, he says, the scores could be affected by whether students attend a charter school, which “destroys the benefits of the randomization” that is a strength of Hoxby’s study.

Reardon, a research methodologist, also faults the Hoxby study for “inappropriately” extrapolating data on students’ achievement gains between kindergarten and 8th grade to calculate learning benefits over their entire school careers and raises some other, equally technical, issues as well.

Reardon’s bottom line: While it makes an important research contribution, the report “likely overstates the effects of New York City charter schools on students’ cumulative achievement, though it is not possible—given the information missing from the report—to precisely quantify the extent of overestimation.”

You can find the full paper at the Web site for the Think Tank Review Project, which posted it on Thursday. The project, which specializes in reviewing studies in the news on hot-button education issues, is a joint project of the University Colorado at Boulder Education and the Public Interest Center and the Arizona State University Education Policy Research Unit.

And here’s a side note: If you think nobody pays attention to all these studies on charter schools, think again. The final guidance issued by the federal Education Department this week for its $4 billion Race to the Top program indirectly references some of that research in relaxing language, in the draft guidelines, that many had interpreted to be an endorsement of charter schools as the chief remedy for failing schools. The new language reads:

Notwithstanding research showing that charter schools on average perform similarly to traditional public schools, a growing body of evidence suggests that high-quality charter schools can be powerful forces for increasing student achievement, closing achievement gaps, and spurring educational innovation.

That first clause sounds to me like a reference to a national study released over the summer by the Center for Research on Education Outcomes, or CREDO, which is also based a Stanford. The wording also partly explains, in a nutshell, why so much of the research on charter schools seems to conflict. Some charter schools are very good and some, not.

A version of this news article first appeared in the Inside School Research blog.