The return to classroom instruction time in private and public schools

Private school students outperform their public school peers on standardized tests. Extensive effort has been devoted to testing whether the private–public gap is attributable to the schools themselves or simply due to peer effects or positive selection into private schools. Receiving far less attention is the extent to which the return to specific schooling inputs differs between private and public schools. We find evidence of an overall positive effect of class time on academic achievement and little evidence of a premium to time in private schools. Indeed, the benefit of added time appears similar in both settings. The lack of a private school premium to class time is consistent with the notion of positive selection into private schools.