DRIVING BELIEFS AND BEHAVIORS OF NOVICE ...

DRIVING BELIEFS AND BEHAVIORS OF NOVICE TEEN DRIVERS AND THEIR PARENTS: IMPLICATIONS FOR TEEN DRIVER CRASH RISK

Mary Pat McKay, MD, MPH Brigham and Women’s Hospital Department of Emergency Medicine Boston, MA Jeffrey H. Coben, MD Professor of Emergency Medicine Drexel University College of Medicine Allegheny General Hospital Pittsburgh, PA Gregory Luke Larkin, MD, MSPH Professor of Surgery, Emergency Medicine & Public Health The University of Texas Southwestern Medical Center at Dallas

ABSTRACT This project was a cross sectional survey of 739 matched family pairs of recently licensed teens and their parents. It was designed to assess the relationship of driving behaviors between parents and teens and to investigate predictors of teen crashes. One third of teens reported being involved in a crash during an average of 14 months of driving while 19.9% reported received a moving violation. Teens reported engaging in most risky driving behaviors more frequently than their parents. Teen and parental driving behaviors were associated, but the level of association was low, suggesting that other factors may outweigh parental influence. In multivariate analysis, only the teen’s belief about their crash risk and whether the teen had received a moving violation were associated with reporting a crash.

47th ANNUAL PROCEEDINGS ASSOCIATION FOR THE ADVANCEMENT OF AUTOMOTIVE MEDICINE September 22-24, 2003

In 1999, teenagers accounted for about seven percent of licensed drivers in the United States but were involved in 15 percent of all fatal crashes [NHTSA, 1999]. Of crashes involving teens, the adolescent driver is at fault more than 80 percent of the time and the crash rate for teen drivers is up to 6 times that of older drivers [Ryan, Legge, and Rosman, 1998]. Sixteen-year-old drivers are particularly at risk [MMWR, 1996], and most likely to be the driver at fault [Ulmer, Williams, and Presser, 1997]. The high crash risk for teens is believed to be the result of a combination of immaturity and inexperience. Immaturity is age related and associated with decreased perception of risk, increased willingness to attempt behaviors identified as risky, and higher suggestibility by peers. Inexperience is skills based and associated with less ability to accurately perceive specific road situations, poor estimation of safe turning speeds, traffic gaps, and stopping distances, as well as slowed or inappropriate responses to traffic situations [Deery, 1999]. As part of an evaluation of Pennsylvania’s recently enhanced graduated driver licensing system, a survey of matched pairs of teens and parents was conducted. This provided an opportunity to study the etiology of teens’ risky driving behaviors. With rare exceptions [Hemenway and Solnick, 1993], previous research has tended to focus on personality traits or general attitudes toward risk (immaturity characteristics) rather than on risks specific to driving [Deery and Fildes, 1999; Arnett, Offer and Fine, 1997; Jonah, 1997]. In fact, very little research has evaluated the specific etiology for risky driving behaviors in teens. One recent paper suggests that having a parent with a driving history of three or more reported crashes increases the teenage child’s risk of having a reportable crash. [Ferguson, Williams, Chapline, et al., 2001] The aim of this project was to evaluate the effect of parental beliefs and driving behaviors on teen driving behaviors and crash risk. Finally, the goal was to create a model including both teen and parent behaviors and beliefs that would predict increased crash risk for the teen. METHODS A statewide, random-sample mail survey of teen drivers and their parents was conducted in Pennsylvania. To be eligible, the teen must have been 16 or 17 years old when they obtained an initial learner’s permit and that permit must have been issued between 1 January and 1 July 2000. This ensured that the teens were licensed under the most recent graduated driver licensing system in Pennsylvania. SAMPLE SELECTION - 48,372 teens met inclusion criteria. Assuming a response rate between 20 and 40 percent, surveying

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2500 families was expected to result in enough matched family pairs to allow for multivariate regression to be performed using both parent and teen driving behaviors as predictors. Because there was no previous data on responses from matched pairs, no formal power analysis was performed. A random sample of 2500 teens (and their parents) were selected and packets were mailed to the addresses available in the Pennsylvania driver license database. A total of 739 matched pairs responded and are included in this analysis. SURVEY DESIGN - The survey was created using previously performed telephone surveys [PennDOT Junior License Survey; California New Driver Survey] and published results as a starting point [MMWR, 1994; Williams, Ferguson, Leaf, et al., 1998; Ferguson and Williams, 1996; Begg, Langley, Reeder, et al., 1995]. After consensus regarding the questions was reached among the research team, the questions were tested in eight focus groups held in Western PA during October, 2000. These groups included both teens and parents. Questions that were unclear or difficult to respond to or those that created discomfort for the teens or parents (such as questions surrounding alcohol) were re-written or removed from the survey. Data on length of supervised driving during the learner phase were collected as these were thought to correlate with teen crash risk. In addition to the number of crashes and violations throughout the driving period, data on current driving behavior, including frequency of cell phone or radio use, speed, and six specific driving behaviors were requested from each driver. Previous work on aggressive driving or willingness to engage in risky driving behaviors has focused on generalized personality traits, psychiatric illness, alcohol use, and age related willingness to take risks [Deery and Fildes, 1999; Donovan, Marlatt and Salzberg, 1983, Jonah, 1986; Stevenson, Palamara, Morrison, et al., 2001]. This work suggests more deviant personality types, hyperactive teens [Nada-Raja, 1997], and generally increased aggressiveness are associated with an increased risk of teen crashes. Rather than focus on risky behaviors in general, this study concentrated on driving behaviors. Of these behaviors, two were identified as potentially protective; one was thought to identify driver aggressiveness; and three are risky behaviors. The two protective behaviors were personally wearing a seat belt and ensuring that passengers were wearing theirs. Shouting, gesturing, or blowing the horn were combined and used as a category of potentially aggressive behaviors. Crossing into an oncoming lane of traffic to pass, speeding up to run through a yellow light, and tailgating another driver may place the driver at increased risk of a crash [Retting, Williams, Preusser, et al., 1995; Retting, Ulmer and Williams, 1999]. Finally, subjects were

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asked to evaluate teen crash risk as a whole and to compare their personal crash risk to others of the same age. Because this project involved minors, implied consent was obtained from the parents by addressing the entire survey package “To the Parents of – “. Parental consent and assent of the minor was assumed if surveys were returned. Two return envelopes were provided to allow teens to respond without the oversight of their parents. An incentive was used, consisting of an entry for each returned survey into a lottery to win one of four $100 gas cards. Expedited approval was received from the Institutional Review Board of Allegheny General Hospital prior to beginning this study. DATA ANALYSIS – Responses between the parent and teen groups were initially compared using χ2 or McNemar where appropriate. In addition, the kappa statistic and/or correlation methods were applied to compare the responses of the matched pairs of teens and their parents for each behavior. Then, using whether or not the teen had reported having had a crash as the outcome variable, the behavior reports of both groups were tested for univariate association. Finally, those behaviors or beliefs that were univariately associated with the outcome were analyzed using multivariate logistic regression. Analysis was performed using SPSS (v.11, 2001) and Primer of Biostatistics [Glantz, 1996]. Significance was set with α = 0.05. RESULTS DEMOGRAPHICS – A total of 739 matched pairs of teens and parents responded to the survey. The teen survey respondent group did not significantly differ from the population or the sampled group on age and gender. The majority of respondents (56.3%) were 17, 42.2% were 18 and 1.5% were 19 years old at the time they responded to the survey. 53.3% of the teen respondents were female. All but 14 of the teens had advanced to junior licensure, and 47.8% had achieved a regular license. The majority (74.4%) of the parent respondents were female. 95.8% of the respondents were white and over 47.9% of those answering the income question had household incomes above $60,000. These numbers are not consistent with the general population of Pennsylvania. To evaluate this further, geocoding was performed comparing the sample group and the respondent group to census tracts by car ownership. With greater than 75% matching, there was excellent correlation for both the sample and the respondents to geographic areas of higher vehicle ownership. There was no significant geographic difference between the sample and the respondents. This implies but does not prove that the bias exists in the eligible population rather than the respondent group.

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Although the small proportion of non-white respondents did not allow subgroup analysis by race, such analysis was performed by income. This resulted in significant differences only on two questions: speeding, where both teens and parents of higher income report speeding more frequently; and cell phone use, where both groups were more likely to report using a cell phone while driving if they were of higher income (p