1. School of Nursing, Columbia University, New York, New York, USA;
2. Quantitative Methods in the Social Sciences, Columbia University, New York, New York, USA;
3. College of Physicians & Surgeons, Columbia University, New York, New York, USA;
4. Department of Health & Kinesiology, Texas A & M University, College Station, Texas, USA;
5. Social Intervention Group, Columbia University, New York, New York, USA