Background: Motorcycle safety has received much attention from both researchers and policymakers in the United States (US), especially because motorcycle fatalities and injuries are increasing at the same time that overall motor vehicle fatalities have been decreasing. To our knowledge, no study has linked trends in gasoline prices with new motorcycle sales in the US. New motorcycle sales data are more likely to be associated with less experienced riders who may be entering motorcycling in response to escalating gasoline prices. We compare trends in gasoline prices with industry-provided data on new motorcycle sales, and then estimate the impact of new motorcycle sales on crash fatalities. Methods: Data come from the Motorcycle Industry Council and Fatality Analysis Reporting System for 1984-2009. Autoregressive integrated moving average (ARIMA) regression is used to model the relationship of inflation-adjusted gasoline prices with sales. The impact of these new sales on fatalities is estimated. Results: New motorcycles had their lowest sales with 186,000 units in 1992 and, afterward, grew every year until 2008, reaching 888,000 units—a 400% increase. Sales and gasoline prices are highly correlated (r=.78). ARIMA regression modeling predicts that for every $1 increase in gasoline prices, there are an additional 286,000 new motorcycle sales in the US (p<.001). When inflation-adjusted gasoline prices increased by 117% from 1998-2008, this was associated with an increase in sales of 528,000, but this resulted in 438 additional motorcycle fatalities. Conclusions: Although prior research shows a negative relationship between gasoline prices and driving, we present evidence that gasoline prices may be increasing incentives to purchase motorcycles, leading to an increase in fatalities from motorcycle crashes. These findings lend support to traffic safety initiatives to improve motorcycle safety gear and training requirements for new motorcycle riders.
Available at: http://works.bepress.com/peter-hilsenrath/153/