Class size and teacher effects in higher education

• We use a discontinuity in the determination of class size to identify causal effects of class size on student assessments of professors.
• We also identify the performance of first time teachers.
• We are able to compare a policy of increasing class size to one of opening new sections taught by first time teachers.
• We give a numerical magnitude to the tradeoffs involved when deciding how to handle an increase in admissions.

Using student evaluations of their instructor as an outcome measure, we estimate and compare class size and teacher effects for higher education, with an emphasis on determining whether a comprehensive class size reduction policy that draws on the hiring of new teachers is likely to improve educational outcomes. We find that first time teachers perform significantly worse than their peers, and we find substantial class size effects. Hence higher education institutions face a tradeoff if they wish to increase admission. This tradeoff implies that as class size increases, at first the negative class size effect is smaller than that of introducing a first time teacher. However, beyond a certain level, the class size effect dominates and it is better to create a new class with a first time teacher.1