Affiliation: | (1) Division of Preventive Medicine, Department of Basic Medical Science, Hebei Medical University, Shijiazhuang, PR China;(2) Department of Biostatistics, School of Public Health, Harbin Medical University, Harbin, PR China;(3) Department of Economics, University of Calgary, Calgary, Canada;(4) Department of Community Health Sciences and Centre for Health and Policy Studies, University of Calgary, Calgary, Canada |