1. Human Development & Family Science, College of Education and Human Ecology, The Ohio State University, Columbus, Ohio.
2. Columbus Children's Center for Injury Research and Policy, Columbus Children's Hospital, Columbus, Ohio.
3. Center for Health Studies, Group Health Cooperative, Seattle, Washington.
4. Harborview Injury Prevention and Research Center Seattle, Washington.
5. Departments of Epidemiology and Pediatrics University of Washington, Seattle, Washington.