Unobserved heterogeneity has been recognized as a critical issue in traffic safety research
that has not been completely addressed or often overlooked, and can lead to biased
estimates and incorrect inferences if inappropriate methods are used. This paper uses a
latent class approach to investigate the factors that affect crash severity outcomes in single-
vehicle motorcycle crashes. Motorcycle crash data from 2001 to 2008 in Iowa were collected
with a total of 3644 single-vehicle motorcycle crashes occurring during that time period. A …