1. Public Health Program, Khon Kaen University, Khon Kaen, Thailand
2. Faculty of Nursing, Ratchathani University, Udonthani, Thailand
3. Department of Epidemiology and Biostatistics, Faculty of Public Health, Khon Kaen University, Khon Kaen, Thailand
4. Center of Excellence in Biostatistics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand