Marcus Winters, who follows education for the Manhattan Institute, has released a paper showing that even students who don’t attend a charter school benefit academically when their public school is exposed to charter competition.

Mr. Winters focuses on New York City public school students in grades 3 through 8. “For every one percent of a public school’s students who leave for a charter,” concludes Mr. Winters, “reading proficiency among those who remain increases by about 0.02 standard deviations, a small but not insignificant number, in view of the widely held suspicion that the impact on local public schools . . . would be negative.” It turns out that traditional public schools respond to competition in a way that benefits their students. […]

One of the most encouraging findings by Mr. Winters is how charter competition reduces the black-white achievement gap. He found that the worst-performing public school students, who tend to be low-income minorities, have the most to gain from the nearby presence of a charter school. Overall, charter competition improved reading performance but did not affect math skills. By contrast, low-performing students had gains in both areas, and their reading improvement was above average relative to the higher-performing students.