1. Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814.
2. Department of Health Policy and Management, Texas A&M University School of Public Health, 1266 TAMU, College Station, TX 77843.
3. Department of Statistics, Texas A&M University, 3143 TAMU, College Station, TX 77843.
4. Department of Management, Policy, and Community Health, The University of Texas School of Public Health, 1200 Pressler Street, Houston, TX 77030.