aInstitute of Business and Economic Research, USA
bSchool of Public Health, University of California, Berkeley, California, USA
cDepartment of Epidemiology, USA
dDepartment of Global Health, University of Washington, Seattle, Washington, USA.
Received 8 June, 2010
Accepted 16 June, 2010
Correspondence to Dr Sandra McCoy, MPH, PhD, F502 Haas Building, University of California, Berkeley, CA 94720, USA. Tel: +1 510 332 6612; e-mail: email@example.com