1. Biostatistics/Epidemiology/Research Design Core, Center for Clinical and Translational Sciences; The University of Texas Health Science Center at Houston; Houston; TX; U.S.A.
2. Yale University School of Nursing; New Haven; CT; U.S.A.
3. Department of Epidemiology and Biostatistics, College of Human Medicine; Michigan State University; East Lansing; MI; U.S.A.
4. Division of Biostatistics, School of Public Health; University of Texas Health Science Center at Houston; Houston; TX; U.S.A.