[1] Harvard Med Sch, Dept Hlth Care Policy, Boston, MA USA
[2] Univ Calif Los Angeles, Calif Ctr Populat Res, Los Angeles, CA 90095 USA
[3] Univ Calif Los Angeles, Dept Stat, Los Angeles, CA USA
[4] Univ Michigan, Ctr Populat Studies, Inst Social Res, Ann Arbor, MI USA
[5] Univ Michigan, Inst Social Res, Survey Res Ctr, Ann Arbor, MI USA
[6] Univ Calif Los Angeles, Fielding Sch Publ Hlth, Los Angeles, CA 90095 USA