1. MRC Biostatistics Unit Cambridge U.K.
2. Centre for Reviews and Dissemination University of York York U.K.
3. Health Services Research Unit University of Aberdeen Aberdeen U.K.
4. Bristol Heart Institute University of Bristol, Bristol Royal Infirmary Bristol U.K.
5. Public Health, Epidemiology and Biostatistics University of Birmingham Birmingham U.K.
6. Community Information and Epidemiological Technologies, Institute of Population Health University of Ottawa Ottawa Canada
7. College of Education and Human Development University of Louisville Louisville KY USA
8. Department of Medicine University of Ottawa
9. Department of Epidemiology and Community Medicine University of Ottawa Ottawa Canada