[1] Brandeis Univ, Heller Sch Social Policy & Management, Inst Child Youth & Family Policy, Waltham, MA 02453 USA
[2] Queens Univ, Queens Management Sch, Belfast BT9 5EE, Antrim, North Ireland
[3] UKCRC Ctr Excellence Publ Hlth Northern Ireland, Belfast, Antrim, North Ireland
[4] Ottawa Hosp Res Inst, Clin Epidemiol Program, 725 Parkdale Ave, Ottawa, ON K1Y 4E9, Canada
[5] Brown Univ, Sch Publ Hlth, Dept Epidemiol, 121 South Main St, Providence, RI 02912 USA
[6] Boston Univ, Dept Earth & Environm, 675 Commonwealth Ave, Boston, MA 02215 USA
[7] Harvard Univ, Ctr Populat & Dev Studies, 9 Bow St, Cambridge, MA 02138 USA