Age-Period-Cohort Analysis of Young Drivers in Fatal Motor Vehicle Crashes

Background/Purpose:

Motor vehicle crashes are the leading cause of death for adolescents in the United States, accounting for 31% of fatalities in 15-24 year olds in 2005. To better understand these fatalities, fatal motor vehicle crash rates among young drivers are examined from 1982-2005.

Methods:

Rates of drivers 14-21 years in fatal crashes from 1982-2005 were examined using Fatality Analysis Reporting System and U.S. Census Bureau data. An Age-Period-Cohort (APC) analysis was conducted to assess cohort effects. Cohort effects illustrate birth year specific changes in motor vehicle crash rates caused by changes in the environment or society. Cohort effects were examined using: 1) graphical presentation, 2) median polish methods, and 3) linear regression of median polish residuals on birth cohort.

Results/Outcomes:

Linear regression models of median polish residuals showed that drivers born from 1986-1991 had lower fatal crash rates than drivers born in 1976. These results showed the presence of a statistically significant cohort effect in drivers of both sexes, with a steeper decline in females.

Conclusions:

This age-period-cohort analysis shows significant cohort effects, manifesting in decreasing fatal crash rates for drivers aged 14-21 born from 1986-1991, particularly in female adolescents. Knowledge of how these rates change over time aids in the generation of hypotheses that may explain protective factors.