Scott, JAGJAGScottBauni, EEBauniMoisi, JCJCMoisiOjal, JJOjalGatakaa, HHGatakaaNyundo, CCNyundoMolyneux, CSCSMolyneuxKombe, FFKombeTsofa, BBTsofaMarsh, KKMarshPeshu, NNPeshuWilliams, TNTNWilliams2014-04-292012-06-012014-04-292012International Journal of Epidemiology, 2012, 41 (3), pp.650-6570300-5771http://hdl.handle.net/10044/1/1369729/04/14 meb. Open access paper OK, to add© The Author 2012; all rights reserved. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.comJournal Articlehttps://www.dx.doi.org/10.1093/ije/dys062