[1] Department of Public Health Sciences, Sect. on Social Sci. and Hlth. Plcy., Bowman Gray School of Medicine, Winston-Salem, NC
[2] Div. of Epidemiol. and Clin. Applic., Field Studies and Biometry Branch, Natl. Heart, Lung, and Blood Inst., Bethesda, MD
[3] Demogr. Statistical Methods Division, Bureau of the Census, Washington, DC
[4] Human Population Laboratory, California Dept. of Health Services, Berkeley, CA
[5] Department of Public Health Sciences, Sect. on Social Sci. and Hlth. Plcy., Bowman Gray School of Medicine, Winston-Salem