1. Department of Statistics, Quaid-i-Azam University, Islamabad, Pakistan
2. Faculty of Health Studies, University of Bradford, Bradford BD7 1DP, UK
3. Bradford Institute for Health Research, Bradford Teaching Hospitals NHS Foundation Trust, Bradford, UK
4. Arriyadh Community College, King Saud University, Riyadh, Saudi Arabia
5. KSA Workers University, El-Mansoura, Egypt
6. College of Business Administration, King Saud University, Al-Muzahimiyah, Saudi Arabia
7. Department of Mathematics, College of Science, King Khalid University, Abha 61413, Saudi Arabia
8. Department of Mathematics and Statistics, Faculty of Basic and Applied Sciences, International Islamic University, 44000 Islamabad, Pakistan