1 Department of Family Medicine and Community Health, University of Minnesota, Minneapolis, Minnesota, USA. Electronic address: stovitz@umn.edu.
2 Department of Epidemiology and Environmental Health, School of Public Health and Health Professions, University at Buffalo, The State University of New York, Buffalo, New York, USA.
3 Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montréal, Québec, Canada.