This study examines how social circumstances infuence the educational performance of students taking the National Secondary Education Examination (ENEM). We will use two theoretical frameworks. Initially, we adopt the Roemer Identification Axiom, i.e., we assume independence between background and effort. After that, we relax this hypothesis seeking to measure the bias of omission of individual effort and talent. The first set of results shows strong difference in effort between types to obtain a good ENEM performance. The most striking result is that the indirect effect of mother's education is 2.36 times larger than the direct effects.
