1 RAND Corporation (A.H.), Pittsburgh, Pennsylvania 15213, USA; RAND Corporation (R.A.P., J.M.T.), Arlington, Virginia 22202, USA; RAND Corporation (M.N.E., M.D.), Santa Monica, California 90401, USA; Brown University School of Public Health (J.M.T.), Providence, Rhode Island 02903, USA. Electronic address: ahaas@rand.org.
2 RAND Corporation (A.H.), Pittsburgh, Pennsylvania 15213, USA; RAND Corporation (R.A.P., J.M.T.), Arlington, Virginia 22202, USA; RAND Corporation (M.N.E., M.D.), Santa Monica, California 90401, USA; Brown University School of Public Health (J.M.T.), Providence, Rhode Island 02903, USA.