Matthew Kahn on Charter Schools

Caroline Hoxby has found that students who were randomly selected to attend charter schools earned better test scores than other students who applied for charter schools but lost the lottery. This research controls for an important factor in charter students’ achievement: motivation to attend charters. You can’t compare scores for students who enroll in charters with the group of traditional public school students as a whole, because applying to a charter indicates an extra degree of commitment. By restricting the study to students who applied, Hoxby shows that charter school attendance, not initial motivation, accounts for the difference in achievement.

Matthew Kahn (scroll down to the Sept. 28 post) wonders how much of this effect can be attributed to what goes on in the classroom. He suspects that when parents see that their child’s new school is better than the old one, they work harder to supplement the child’s education at home. For instance, they might be more careful in checking that homework is completed on time.

I think this parental response probably does account for part of the charter effect. Caroline Hoxby herself points out in her talks about charters (you can watch one here) that parents may approach education differently when they’ve chosen a school, just as customers expect more from a restaurant they’ve chosen than from an office building cafeteria.

It’s an interesting question from the point of view of econometrics, but less relevant to policy. What matters is that charters spur student achievement. Whether 100 percent of the learning happens in school, or whether some of the benefits come from changes within homes, the fact remains that students who switch to a charter generally do better than their peers who lost the charter lottery. That’s one more good reason to let students attend charters if they want to.