1. National Institute on Aging, NIH/Intramural Research Program, Baltimore, MD 21224
2. Department of Health, Nutrition and Exercise Sciences, University of Delaware, Newark, DE 19716
3. Graduate Program in Public Health, Eastern Virginia Medical School, Norfolk, VA 23501
4. Department of Epidemiology, Michigan State University, East Lansing, MI 48824
5. Statistical Information Systems, MedStar Research Institute, Baltimore, MD 21224