Heterogeneous Class Size Effects: New Evidence from a Panel of University Students

Using administrative records from a UK university, we present evidence on the effects of class size on students' test scores. We estimate non-linear class size effects controlling for unobserved heterogeneity of students and faculty. We find that: ("i") at the average class size, the effect size is - 0.108; ("ii") the effect size is negative and significant only for the smallest and largest ranges of class sizes and zero in intermediate class sizes; ("iii") students at the top of the test score distribution are more affected by changes in class size, especially when class sizes are very large. Copyright (C) The Author(s). Journal compilation (C) Royal Economic Society 2010.