FACTORING IN BRAZIL - AN INFORMATION ASYMMETRY APPROACH It is worth noting that the relative magnitude of μ j may be quite modest. Family background variables typically explain the vast majority of the differences in average student test scores across schools, potentially leaving relatively little room for efficiency (or school value added ) Nevertheless, most observers believe that public school efficiency is important, that it exerts a non-trivial role on the educational outcomes of students, and that it varies substantially across schools
