Because charter schools are relatively new institutions — the first American charter school opened in 1992 — little research has been done on the long-term outcomes for students who attended a charter school relative to those who attended a traditional public school.
But with many former charter-school students now in their twenties, Mathematica Policy Research has conducted a study on long-term educational and earning achievements, finding that charter-school students are more likely to have greater educational success and higher earnings than their traditional public-school peers.
Mathematica found that attending a charter high school leads to a ten to eleven percentage point increase in the probability of attending college and between a 6.6 and 12.6 point increase in the probability of persisting in college at least two consecutive years. The study also found that charter high schools may increase their students’ earnings in their mid twenties by 12.7 percent relative to the earnings that would have been expected had the student attended a traditional public high school.
In order to account for the possibility that only certain types of students are accepted to charter schools, Mathematica studied only students who had attended charter schools up to the eighth grade, comparing those who continued in charter schools through high school and those who went from eighth grade to a traditional high school. They also controlled for race, gender, family income, and test scores.
Notably, when controlling for test scores, charter-school students still outperform their public-school peers post–high school. “Charter high schools seem to be endowing their students with skills that are useful for success in college and career but that are not captured by test scores,” the study found.
Mathematica’s study is by no means conclusive. As Kevin Drum notes, it did not compare students who attended charters with those who wanted to but lost out in the lottery (which is the best way to eliminate the possibility of self-selection bias). As more charter school students come of age, more robust empirical studies are expected.