We present evidence on how farmers' decisions to adopt a new crop relate to the adoption choices of their network of family and friends. We find the relationship to be inverse-U shaped, suggesting social effects are positive when there are few adopters in the network, and negative when there are...

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...