What happens inside New York City charter schools is more important than their ideological affiliations in determining academic success, according to a new paper.

The paper, which did not undergo peer review, is based on a detailed analysis of 35 city charter schools by two Harvard University researchers, Roland Fryer and Will Dobbie. Fryer is a MacArthur “genius” award winner who has conducted experiments and studies in New York City in the past, often in order to test his theories about the impact of incentives.

For the newest paper, “Getting Beneath the Veil of Effective Schools: Evidence from New York City,” the researchers conducted in-depth case studies at self-selecting charter schools that received $5,000 for supplying required information. By interviewing principals, teachers, and students; analyzing test scores and lesson plans; and videotaping classroom activity, Fryer and Dobbie built a database of “the inner workings of schools” and compared them.

They wanted to find which traits of city charter schools appeared most closely linked with academic success. They also asked whether schools with a particular philosophy, such as the “whole child” approach of providing wraparound services or the “no excuses” approach typified by KIPP charter schools, did better than others.

The researchers conclude that teacher credentials, class size, and per-pupil spending did not account for test score differences across the schools, but that five other features did. Those traits — frequent teacher feedback, high rates of data usage, “high-dose” tutoring, more class time, and a culture of high expectations — are features of many charter schools. Without them, schools that adhere to particular philosophies don’t outperform other charter schools, according to the analysis.

This finding seems to have surprised Fryer, who recently engineered an effort to test whether the features of KIPP’s “no excuses”-style charter schools would pay off in Houston’s traditional public schools. (He found they did, at least in math.)

“The fact that the “No Excuses” designation becomes statistically insignificant when one accounts for five policies is striking and highly suggestive that their [sic] is nothing mystical about “No Excuses” schools,” Fryer concludes in the new report.

The complete report: