How New York City's Charter Schools Affect Achievement

Caroline M. Hoxby, Sonali Murarka, and Jenny Kang
New York City Charter Schools Evaluation Project
September 2009

This long-anticipated charter school study brings some very positive findings, at least regarding New York City. Using gold-standard lottery-based analysis, Hoxby and her colleagues compare the achievement of 93 percent of Big Apple charter school students who were "lotteried-in" with those public-school students who were "lotteried-out" in schools open through 2005-2006. This means that the authors took one population of students (those applying to typically oversubscribed charter schools) and compared the randomly selected ones who got in (lotteried-in) to the ones who didn’t (lotteried-out) and remained in traditional schools; this method controls for a host of typically immeasurable factors like student motivation and family attitude toward education. Turns out that, when compared with his or her lotteried-out counterpart, each year spent by a pupil in a charter school equals a three point gain on the state Regents test, above typical grade-level progress. That means that, after four years in a charter school, a lotteried-in student would score 12 points higher. Furthermore, students who were enrolled in a charter school from kindergarten through eighth grade scored roughly 30 points higher on the state math exam and 23 points higher on the state English language arts exam, than their lotteried-out complements who remained in a traditional public school. This report is chockablock with other interesting data, including common organizational and pedagogical themes in the charter schools that were examined, as well as an analysis of the racial and socioeconomic backgrounds of NYC charter pupils. (See this Wall Street Journal coverage, for example.) And despite its intricate methodology, it's easy to read. That said, remember that it deals only with the Big Apple, meaning that its findings do not settle anything about the charter conversation elsewhere. Read it here.

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