In this paper, we estimate the extent of ability peer effects in the classroom and explore the underlying mechanisms through which these peer effects operate. We identify as low ability students those who are enrolled at least one year behind their birth cohort ("repeaters"). We show that there...

This paper argues that terrorism, beyond its immediate impact on innocent victims, also raises the costs of crime, and therefore, imposes a negative externality on potential criminals. Terrorism raises the costs of crime through two channels: (i) by increasing the presence and activity of the...