Q1. What are the contributions in "Peer effects and academic achievement regression discontinuity approach" ?
In this paper, I study ability peer effects in an Icelandic high school. An important feature of this system is that the same teachers teach high-ability and normal classes, both types of classes follow a common curriculum and all students take the same exams. Furthermore, the system is unofficial so students are in most cases not aware of it before they have started their studies. I find that sorting students into high-ability classes does have significant and sizable effect on the academic achievement of students around the assignment threshold, i. e., the results suggest that being assigned to a high-ability class increases academic achievement by 0. 23 standard deviations.