1. Department of Statistics, Faculty of Natural and Agricultural Sciences University of Pretoria Hatfield South Africa
2. Department of Mathematical Statistics and Actuarial Science, Faculty of Natural and Agricultural Sciences University of the Free State Bloemfontein South Africa
3. Department of Statistics, Faculty of Science King Abdulaziz University Jeddah Saudi Arabia
4. Department of Mathematical and Actuarial Sciences, Lee Kong Chian Faculty of Engineering and Science Universiti Tunku Abdul Rahman, Cheras Kajang Selangor Malaysia
5. Department of Statistics, College of Science, Engineering and Technology University of South Africa Pretoria South Africa