1. Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02140;
2. Department of Statistics and Operations Research, University of North Carolina, Chapel Hill, North Carolina 27599;
3. Analytical Partners Consulting LLC, Research Triangle Park, North Carolina 27709;
4. School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599;
5. Roundtable Analytics, Inc., Research Triangle Park, North Carolina 27709;
6. School of Nursing, Duke University, Durham, North Carolina 27710