NEW YORK — On June 4, 1991, Minnesota Gov. Arne Carlson signed into law a bill that set in motion one of the most significant — and controversial — education reform movements in modern history.Minnesota’s charter school law allowed educators and other concerned individuals to apply to the state for permission to operate a government-funded school outside of the public education system. To obtain and keep their licenses, these new schools needed to show they were serving their students effectively, based on goals laid out in the school’s “charter.”City Academy, America’s first charter school, opened in St. Paul the following year. Its mission was to get high-school dropouts on track to vocational careers, and it is still operating today.Whether charter schools have actually lived up to their initial promise is a hotly contested topic in the education reform debate. The latest findings, based on six well-regarded charter schools in Boston, released this week by the Boston Foundation and MIT’s School Effectiveness and Inequality Initiative, adds to the accumulating evidence that at least a subset of high-performing charters are measuring up to the movement’s early aspirations of giving disadvantaged kids a shot at a better life. The study shows that the Boston schools’ students did better on SAT and Advanced Placement tests and are vastly more likely to enroll at four-year colleges — and to do so on scholarship — than otherwise identical students in the Boston public school system.What makes a charter school different from other public schools? While they’re funded with public money, they generally operate outside of collective bargaining agreements and other constraints that often prevent principals in public schools from innovating for the good of their students (so the argument goes). In exchange for this freedom, they generally get less funding than public schools (though they’re free to look for private donations, and many do) and have to prove that they are making good on the promises set out in their charters, which often means showing that they improve their students’ performance on statewide standardized tests.It’s an idea that’s resonated with a surprisingly wide swath of American society, from free-marketeers who like the idea of reducing government involvement in education to anti-poverty activists frustrated by the slow rate of social progress.Others are less sanguine about the charter approach. School unions, for example, have been cautious in their support, often seeing charters as drawing funds away from resource-starved districts and diverting the discussion from how to fix public schools, which continue to serve the vast majority of American students.At least part of the disagreement revolves around whether charter schools deliver on their promise to improve student outcomes. You might think this is a relatively easy proposition to evaluate. But any effort to compare performance is confounded by the fact that the kinds of parents who take steps to enroll their children in charter schools may be the kind of motivated and supportive parents whose children would have done just fine in any school system. And if the longer hours and additional school days that are a feature of many charter schools lead underperformers to drop out, the select group that remains may again be made up of those who would have tested well in any school environment.But for at least a subset of charter schools, researchers can come fairly close to running a clinical trial where some applicants are enrolled at charters and others are left in the public system purely by chance. The reason is that many charter schools are oversubscribed, and their scarce spots are allocated through a lottery.Numerous studies have used this lottery method to analyze the impact of charter schools on standardized test scores, and by and large they report similar findings: Charters in rural or suburban areas don’t do any better than public schools, while in urban areas they are associated with greater test score improvements in math and language. But another important point from past studies is that there is enormous variation in the effectiveness of charter schools. There are some great ones but also some real duds.
Ray Fisman is the Lambert Family professor of social enterprise and director of the Social Enterprise Program at the Columbia Business School.