1. Pediatric Research Consortium;
2. Pediatric Generalist Research Group;
3. Divisions of General Pediatrics and
4. Emergency Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania;
5. Department of Pediatrics, Children's Hospital of Philadelphia-Westat Biostatistics and Data Management Core, Philadelphia, Pennsylvania; and
6. Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania