Seventy-five percent of charter school studies are flawed because they fail to account for charter students’ differences in academic background and performance, according to a meta-analysis published in Science.
High-quality research is emerging from charters that use lotteries to pick students, write Julian R. Betts, a professor of economics at the University of California, San Diego, and Richard C. Atkinson, a former president of the University of California system who once served as director of the National Science Foundation. Students who apply to a charter but lose the lottery represent a sound control group, they write.
The relatively small number of lottery-based studies of charter schools have generally shown that they either outperform or perform at the same level as traditional public schools, according to the authors. But those studies cover only a small fraction—about 2 percent—of charter schools nationally.
However, charters that need lotteries for admission may be unusually good schools, the authors warn.