1. Center for Injury Research and Prevention, Children's Hospital of Philadelphia Research Institute, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
2. Annenberg Public Policy Center, University of Pennsylvania, Philadelphia
3. Wharton School, University of Pennsylvania, Philadelphia
4. School of Public Health, University of Michigan, Ann Arbor
5. Institute for Social Research, University of Michigan, Ann Arbor
6. Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia Research Institute, Philadelphia
7. Division of General Pediatrics, University of Pennsylvania Perelman School of Medicine; Philadelphia