Marcus Winters: Data proves charter schools work

Recent evidence confirms what advocates and parents have long known to be true: Charter schools work. Free of collective bargaining agreements and other restrictions imposed on traditional public schools, charters deliver outsize academic benefits to those students who are lucky enough to attend them.

But what about the kids who get "left behind?" What effect do charters have on the vast majority of students who are not lucky enough to attend them? Critics have long maintained that the success of charter schools comes only at the expense of traditional public schools. New evidence from New York City, however, reveals that charter schools do no harm to students in traditional public schools. In fact, charter competition correlates with a modest increase in reading proficiency for traditional public school students.

Less than two decades since the first experimental charters opened in Minnesota, 1.4 million students across forty-one states and the District of Columbia are enrolled in over 4,500 charter schools. Policymakers from across the political spectrum, including President Obama, have pushed to expand the number of charter schools.

Several urban public school systems have seen dramatic reductions in enrollments over the last two decades. Charters frequently take the blame for this trend. Since 1970, enrollment in Washington, D.C.'s traditional public schools has dropped by two-thirds--from 150,000 to about 44,000 students--while enrollment in the city's charter schools has grown to about 28,000 students. Detroit public schools have seen an even more dramatic decline in enrollment, down 45 percent since 2004.

With charter schools siphoning away so many students, we'd expect to see some impact on traditional public schools. Critics charge that, since public schools are funded in part on a per-pupil basis, charter schools are bound to diminish their effectiveness by gobbling up financial and human resources. On the other hand, proponents argue that public schools respond to the threat of losing students by working harder to compete for enrollments.

In a new report for the Manhattan Institute, I study the effects of charter competition on students who are "left behind." Using student level data from New York City -- the nation's largest school district and home to a rapidly expanding charter school sector -- I measure the influence of charter competition on the math and reading achievement of traditional public school students.

My findings should allay fears that charters have a negative impact on traditional public schools: Students benefit when their public school faces competition from a charter. Overall, student reading scores improved in traditional public schools that lost students to charter schools. Math proficiency was neither helped nor harmed.

Significantly, the lowest performing students in a public school benefit the most from charter competition. In both math and reading, students with very low proficiency at the beginning of the year made noticeable academic gains when their schools competed with a charter school for their enrollment.

My findings are consistent with a small but growing body of research indicating that public schools respond to competition by improving the quality of the education they offer. In fact, despite howls from critics, no research has ever found that public school students are harmed when their school loses students to a charter.

Everyone wins when charter schools expand. Charters benefit not only the students who attend them but also the students who do not. We should continue to support efforts to open more charter schools across the nation.

Marcus A. Winters is a senior fellow at the Manhattan Institute. His report, "Everyone Wins: How charter schools benefit all New York City public school students" can be read here.