Offsetting or Enhancing Behavior: An Empirical Analysis of Motorcycle Helmet Safety Legislation.

This study uses state-level panel data from a 33-year period to test the hypotheses of offsetting and enhancing behavior with regards to motorcycle helmet legislation. Results presented in this article find no evidence of offsetting behavior and are consistent with the presence of enhancing behavior. State motorcycle helmet laws are estimated to reduce motorcycle crashes by 18.4% to 31.9%. In the absence of any behavioral adaptations among motorcyclists mandatory helmet laws are not expected to have any significant impact on motorcycle crash rates. The estimated motorcycle crash reductions do not appear to be driven by omitted variable bias or nonclassical measurement error in reported crashes. Overall, the results strongly suggest that mandatory helmet laws yield significant changes in motorcycle mobility in the form of reduced risk taking and/or decreased utilization.