1. Department of Statistics, Faculty of Science, King Abdulaziz University, Jeddah 21551, Saudi Arabia
2. Department of Statistics and Financial Mathematics, School of Sciences, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, China
3. Department of Mathematics and Statistics, The University of Dodoma, PO. Box: 259, Dodoma, Tanzania
4. Department of Statistics, College of Science Engineering and Technology, University of South Africa, Pretoria, South Africa