According to a new working paper published by the National Bureau for Economic Research, much of the academic progress seen in public charter schools is the result of many schools adopting a “no excuses” attitude toward behavioral issues.

“Schools that adopt an intensive ‘No Excuses’ attitude towards students are correlated with large gains in academic performance, with traditional inputs like class size playing no role in explaining charter school effects,” researchers write. Of course, the normal warning that correlation is not causation applies.