1 RAND Corporation and the Department of Psychiatry, Cambridge Health Alliance, Boston, MA.
2 Department of Biostatistics, Harvard TH Chan School of Public Health, Boston, MA; Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA.
3 Department of Biostatistics, Harvard TH Chan School of Public Health, Boston, MA; Department of Health Care Policy, Harvard Medical School, Boston, MA. Electronic address: sharon@hcp.med.harvard.edu.