1 Health Research Group, Department of Statistics, University of Rajshahi, Rajshahi, 6205, Bangladesh
2 National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Department of Orthopaedic Surgery, University of Malaya, Kuala Lumpur, Malaysia
3 Department of Community Medicine, Faculty of Medicine, Sohag University, Sohag, Egypt
4 Sections of Orthodontics and Oral Biology, School of Dentistry, University of California, Los Angeles, California, USA
5 Health Research Group, Department of Statistics, University of Rajshahi, Rajshahi, 6205, Bangladesh. hossain95@yahoo.com