In this paper, we collect data on the inner-workings of 39 charter schools and correlate these data with school effectiveness. We find that traditionally collected input measures -- class size, per-pupil expenditure, teacher certification, and teacher training -- are not correlated with school effectiveness. In stark contrast, we show that an index of five policies suggested by qualitative research -- frequent teacher feedback, the use of data to guide instruction, high-dosage tutoring, increased instructional time, and high expectations -- explains approximately 45 percent of the variation in school effectiveness. The same index provides similar results in a separate sample of charter schools.
Dobbie, Will and Richard Fryer. "Getting Beneath the Veil of Effective Schools: Evidence from New York City." American Economic Journal: Applied Economics 4.5 (October 2013): 28-60.