1. Department of Mathematics and Statistics, Room# 228, Maryam Block, Sector H-10 International Islamic University Islamabad, Islamabad, Pakistan
2. Department of Health Policy and Community Health, Jiann-Ping Hsu College of Public Health, Georgia Southern University, P.O. Box 8015 Statesboro, GA 30460, Statesboro, Georgia
3. Department of Health Policy and Community Health Georgia Southern University, P.O. Box 8015 Statesboro, GA 30460, Statesboro, Georgia
4. International Islamic University Islamabad, Islamabad, Pakistan