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Affiliation
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d Survey Methodology Program, Institute for Social Research, University of Michigan , Rm. 4068, 426 Thompson Street, Ann Arbor , MI 48109. |
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Abstract
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OBJECTIVE Young driver studies have applied quasi-induced exposure (QIE) methods to assess relationships between demographic and behavioral factors and at-fault crash involvement, but QIE's primary assumption of representativeness has not yet been validated among young drivers. Determining whether non-responsible young drivers in clean (i.e., only one driver is responsible) two-vehicle crashes are reasonably representative of the general young driving population is an important step toward ensuring valid QIE use in young driver studies. We applied previously established validation methods to conduct the first study, to our knowledge, focused on validating the QIE representativeness assumption in a young driver population.
METHODS We utilized New Jersey's (NJ) state crash and licensing databases (2008-2012) to examine the representativeness assumption among 17- to 20-year-old non-responsible drivers involved in clean multi-vehicle crashes. It has been hypothesized that if not-at-fault drivers in clean two-vehicle crashes are a true representation of the driving population, it would be expected that non-responsible drivers in clean three-or-more-vehicle crashes also represent this same driving population (Jiang and Lyles 2010 ). Thus, we compared distributions of age, gender, and vehicle type among: (1) non-responsible young drivers in clean two-vehicle crashes and (2) the first non-responsible young driver in clean crashes involving three or more vehicles to (3) all other non-responsible young drivers in clean crashes involving three or more vehicles. Distributions were compared using chi-square tests and conditional logistic regression; analyses were conducted for all young drivers and stratified by license status (intermediate vs. fully licensed drivers), crash location, and time of day of the crash.
RESULTS There were 41,323 non-responsible drivers in clean two-vehicle crashes and 6,464 non-responsible drivers in clean three-or-more-vehicle crashes. Overall, we found that the distributions of age, gender, and vehicle type were not statistically significantly different between the three groups; in each group, approximately one-fourth of drivers were of each year of age 17 through 20, half were males, and approximately 80% were driving a car/station wagon/minivan. In general, conclusions held when we evaluated the assumption within intermediate and fully licensed young drivers separately and by crash location and time.
CONCLUSIONS It appears that the representativeness assumption holds among the population of NJ young drivers. We encourage young driver studies utilizing QIE methods to conduct internal validation studies to ensure appropriate application of these methods and we propose utilization of QIE methods to address broader foundational and applied questions in young driver safety.
Language: en |