Numeracy and Legal Decision Making

Abstract

Health and financial decision-making literatures have chronicled how people’s numerical abilities affect their decisions. Until now, however, there has been no empirical study of whether numeracy — or people’s ability to understand and use numbers — also interacts with legal decision making. This Article presents the first such study, and describes three original findings related to the role of numeracy in legal decision making. First, the study shows a surprisingly high level of math skill among law students, especially given the common folk wisdom that lawyers are bad at math. Second, although prior research in non-legal contexts has shown that people with low numeracy are particularly susceptible to cognitive bias, we detect no significant relationship between law students’ math skills and their susceptibility to bias or framing effects. Finally, and most worryingly, our findings show that the substance of legal analysis varies with math skill for at least some subset of cases.

Keywords: numeracy, math skill, legal decisionmaking, law and psychology, decision making, attorney or lawyer error, perception of risk, empirical legal studies, inefficient precautions, Hand formula

JEL Classification: D81, K00, K10, K13, K32, K1, K2, K3, K4, C00