The impact of class size on the performance of university students

Oriana Bandiera, Valentino Larcinese, and Imran Rasul have a new study on the impact of class size on the performance of university students:

The effect of increasing class size in tertiary education is not well understood. This column estimates the effects of class size on students’ exam performance by comparing the same student’s performance to her own performance in courses with small and large class sizes. Going from the average class of 56 to a class size of 89 would decrease the mark by 9% of the observed variation in marks within a given student. The effect is almost four times larger for students in the top 10%.