OBJECTIVES: The purpose of this study was to measure the effectiveness of Wisconsin's graduated driver licensing law and determine whether a reduction in crash rates was due to reduced exposure, safer driving, or both. METHODS: General population crash rates for 16 and 17 year olds were computed for years before and after graduated drivers licensing. The induced exposure method was used to measure exposure and compute the odds ratio of at-fault crash involvement. RESULTS: For 16 year olds, general crash rates declined 13.8% while injury crash rates declined 15.6%. For 17 year olds, crash rates declined 6.2% for all crashes and 5.8% for injury crashes. There was no statistically significant change in the odds ratio of at-fault crash involvement for 16- or 17-year-old drivers, relative to the reference group. After graduated drivers licensing, 16-year-old drivers were more likely to have at least 1 adult present and less likely to carry 2 or more teen passengers. There was no statistically significant effect on driving habits by time for 16 year olds. CONCLUSIONS: Graduated driver licensing in Wisconsin has resulted in a drop in the general population crash rates for 16 and 17 year olds. This decrease is the result of reduced exposure to the risk of collision rather than safer driving by teens.
OBJECTIVES: The purpose of this study was to measure the effectiveness of Wisconsin's graduated driver licensing law and determine whether a reduction in crash rates was due to reduced exposure, safer driving, or both. METHODS: General population crash rates for 16 and 17 year olds were computed for years before and after graduated drivers licensing. The induced exposure method was used to measure exposure and compute the odds ratio of at-fault crash involvement. RESULTS: For 16 year olds, general crash rates declined 13.8% while injury crash rates declined 15.6%. For 17 year olds, crash rates declined 6.2% for all crashes and 5.8% for injury crashes. There was no statistically significant change in the odds ratio of at-fault crash involvement for 16- or 17-year-old drivers, relative to the reference group. After graduated drivers licensing, 16-year-old drivers were more likely to have at least 1 adult present and less likely to carry 2 or more teen passengers. There was no statistically significant effect on driving habits by time for 16 year olds. CONCLUSIONS: Graduated driver licensing in Wisconsin has resulted in a drop in the general population crash rates for 16 and 17 year olds. This decrease is the result of reduced exposure to the risk of collision rather than safer driving by teens.