Saeid Safiri1, Mohadeseh Sani2, Erfan Ayubi3. 1. Managerial Epidemiology Research Center, Department of Public Health, School of Nursing and Midwifery, Maragheh University of Medical Sciences, Maragheh, Iran; Road Traffic Injury Research Center, Department of Statistics & Epidemiology, Tabriz University of Medical Sciences, Tabriz, Iran. 2. Department of Public Health, School of Public Health, Zabol University of Medical Sciences, Zabol, Iran. 3. Department of Epidemiology, School of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Epidemiology & Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: aubi65@gmail.com.