1. School of Nursing, Mailman School of Public Health, Columbia University, New York, NY
2. Mailman School of Public Health, Department of Epidemiology, Columbia University, New York, NY
3. Mailman School of Public Health, Department of Biostatistics, Columbia University, New York, NY
4. Rollins School of Public Health, Emory University, Department of Biostatistics & Bioinformatics, Atlanta, GA