1. Department of Statistics, Oklahoms State University , Stillwater, OK 74078, USA
2. Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus , Aurora, CO 80045, USA
3. Department of Pediatrics, Section of Allergy and Immunology, University of Colorado Anschutz Medical Campus , Aurora, CO 80045, USA
4. Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Anschutz Medical Campus , Aurora, CO 80045, USA