Leili Abedi1, Homayoun Sadeghi-Bazargani2,3. 1. a Department of Statistics and Epidemiology, Faculty of Health , Tabriz University of Medical Sciences , Tabriz , Iran. 2. b Road Traffic Injury Research Centre , Tabriz University of Medical Sciences , Tabriz , Iran. 3. c WHO Collaborating Center on Safe Community Promotion , Stockholm , Sweden.