What makes a charter school effective?

An interesting question given that charter schools have been in the news recently. From the latest NBER Digest comes this note by Laurent Belsie:

Traditional measures of what makes a good school - small class size, high per pupil spending, and a large share of teachers with advanced degrees but a small share with no certification - don't necessarily determine student achievement, according to a new study of 35 New York charter schools by Will Dobbie and Roland Fryer. Instead, they find that five policies that rarely get measured systematically - frequent teacher feedback, data-driven instruction, intensified tutoring, increased instructional time, and high expectations - can explain roughly half of the variation between more effective and less effective schools. In Getting Beneath the Veil of Effective Schools: Evidence from New York City (NBER Working Paper No. 17632), the authors conclude that these five policies also do a better job of predicting student success than indicators for whether schools offer wrap-around services that serve the "whole child," whether they focus on finding and keeping the best teachers, and whether they use a "No Excuses" approach to teaching.

For this analysis, Dobbie and Fryer amassed a large data base on 35 charter schools that vary widely in their approach to teaching and learning. For example, the Bronx Charter School for the Arts focuses on the arts, while the KIPP Infinity School uses a "no excuses" approach, emphasizing instructional time, parental involvement, and a concentrated focus on math and reading. When the authors study these varied approaches, they find that schools with a larger share of certified teachers actually scored lower in math gains among pupils than other schools. They also find a slightly negative effect on test results for schools with smaller class sizes, higher per pupil expenditures, and a relatively smaller share of uncertified teachers. However, schools that offered feedback ten or more times every semester, and those that tutored students at least four days a week in small groups (six or less), had annual math and English gains that were higher than those of other schools without such programs.

This study comes with two important caveats. First, the five factors that predict student success might be the results rather than the causes of school effectiveness. The authors didn't study other potentially important inputs, such as the principal's skills, or the effects of the lottery system in selecting students. Second, this study didn't examine all of New York City's charter schools, so there may be other dynamics at work that make it hard to generalize the results for other charter schools or public schools.

The authors summarize their findings by writing that: "While there are important caveats to the conclusion that these five policies can explain significant variation in school effectiveness, our results suggest a model of schooling that may have general application."