Studies analyzing motorcycle rider fatalities in the
medical literature have uniformly recommended helmet
laws as a means to prevent deaths among motorcyclists
in the US (Sosin et al., 1990; Fleming and Becker, 1992;
Muelleman et al., 1992; Kraus et al., 1994; Sarkar et al.,
1995; Mock et al., 1995; Rowland et al., 1996). The
nonmedical literature has made similar recommendations,
although less uniformly. Nonmedical reports outlining
the paradoxical effects of motorcycle helmet laws
have offered useful contradictory evidence for consideration
by lawmakers (Goldstein, 1986; Graham and Lee,
1986). Most recently, a report from the US Department
of Transportation’s National Highway Traffic Safety
Administration (NHTSA) has brought to light the finding
that motorcycle fatality rates are lower in states
without helmet laws (National Highway Traffic Safety
Administration, 2000).
Although these studies describe the relationship between
the existence of helmet laws and motorcycle rider
death rates, they do not simultaneously account for the
intervening effects of other variables such as population
density, weather, alcohol consumption, and urban versus
rural roads. Our study seeks to build on previous
work, in both the medical and nonmedical literature, by
better investigating the finding that motorcycle rider
death rates are significantly lower in states without
helmet laws.
2. Methods
2.1. Statistical modeling
The goal of our study was to complete a national,
State-based analysis of motorcycle rider death rates in
the US. Counts of motorcycle rider deaths for all the 50
states and the District of Columbia were obtained from
NHTSA’s Fatality Analysis Reporting System (FARS)
