Harvard economist Caroline M. Hoxby has just issued the most effective rejoinder to the misleading AFT “study” of charter school achievement that’s been much in the news of late: she’s done a far better study, and it yields far different results. Whereas the AFT relied on a small NAEP sample of charter schools and had no way to compare their students’ performance with that of similar youngsters in similar communities, Hoxby obtained 4th grade achievement data for 99 percent of all charter students and compared them with similar test results from the geographically nearest district-operated school or, in some circumstances, a school that’s not quite as close in miles but closer in racial composition. Moreover, the measure she used is one that actually counts for children and schools: the percentage of youngsters in a school who attain proficiency on their state’s test according to their state’s standards (in 2002-3).

For the country as a whole, she found, “Charter school students are 3.8 percent more likely to be proficient on their state’s reading examination when compared to students in the nearest public school. They are 4.9 percent more likely . . . when compared to students in the nearest public school with a similar racial composition.” (The corresponding “charter advantage” in math is 1.6 and 2.8 percent.) On the whole, she concludes, “The average charter school student in the United States benefits from having a charter school alternative.” Moreover, charter pupils do better in reading in fifteen states; the same in five; and worse only in North Carolina. (In math, they fare better in eleven jurisdictions; the same in eight, and worse in North Carolina and Texas.) As Hoxby acknowledges, it’s not a perfect study; like the NAEP-based analysis, it’s a snapshot of student performance at a single point in time and does not show “value added.” Nor is it based on randomized assignment of children to charter and district schools. But it’s promising enough, as the author remarks, not to blow the whistle on charter schools, as the AFT and their allies would do, but to “make us patient enough to wait for the results of multi-year studies based on random lotteries among charter school applicants.” Hoxby herself is working on such studies.

View the PDF here.