1MRC Biostatistics Unit, Institute of Public Health, Cambridge, United Kingdom
2Centre for Statistics in Medicine, University of Oxford, Oxford, United Kingdom
3Nordic Cochrane Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
4Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
5Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
6Preventive and International Health Care Unit, Norwegian Knowledge Centre for the Health Services, Oslo, Norway
7Department of Social Medicine, University of Bristol, Bristol, United Kingdom
8FHI, Research Triangle Park, NC, US