students in economics. We manipulated the composition of groups to achieve a wide range of support, and assigned students … students of low and medium ability gain on average 0.2 SD units of achievement from switching from ability mixing to three …-way tracking. Their dropout rate is reduced by 15 percentage points (relative to a mean of 0.6). High-ability students are …

chooses a science major and on his or her cumulative GPA. Conversely, students who attend campuses with stronger peers in the … sciences are less likely to graduate with a science degree. Weaker, non-minority students typically react to stronger peers in …

), within school-cohort and teacher-group, was not chosen by the students and it was as good as random. We find that male … students graduating from classes with at least 80% of male peers were more likely to choose "prevalently male" (PM) college …