1. Department of Pediatrics, Texas Children's Cancer Center; Baylor College of Medicine; Houston Texas
2. Children's Medical Center; University of Texas Southwestern Medical Center; Dallas Texas
3. Seattle Children's Hospital; University of Washington, and Fred Hutchinson Cancer Research Center; Seattle Washington
4. Division of Pediatric Epidemiology and Clinical Research, Department of Pediatrics; University of Minnesota; Minneapolis Minnesota
5. Department of Mathematics and Statistics; University of New Mexico; Albuquerque New Mexico
6. Division of Epidemiology and Biostatistics, Department of Internal Medicine; University of New Mexico; Albuquerque New Mexico