Monotonicity among Judges: Evidence from Judicial Panels and Consequences for Judge IV Designs

Abstract

Judge IV designs rely on monotonicity—each judge being weakly stricter than more lenient judges in all cases. I measure monotonicity in judicial panels in five different settings and find that it is violated in up to fifty percent of non-unanimous cases. The monotonicity violations are not detected by conventional tests. But they would typically induce little bias in judge IV estimates.

Keywords: instrumental variables, monotonicity, judge IV designs

JEL Classification: C26, K42