1. Division of General Pediatrics, Childrens Hospital Los Angeles, Los Angeles, California
2. Center for Pediatric Health Outcomes Research, Department of Pediatrics, University of Southern California, Los Angeles, California
3. Division of Biostatistics and Outcomes Assessment, Los Angeles County+University of Southern California Medical Center, Los Angeles, California
4. Department of Pediatrics, University of California, Los Angeles, Los Angeles, California
5. Southern California Evidence-Based Practice Center, Rand, Santa Monica, California
6. Statistics Group, Rand, Santa Monica, California
7. Health Services Research and Development Service, Greater Los Angeles Veterans Affair Healthcare System, Los Angeles, California