1. School of Industrial Engineering, North-West University, Potchefstroom, South Africa
2. Focus Area for Pure and Applied Analytics, North-West University, Potchefstroom, South Africa
3. Department of Mathematical Statistics and Actuarial Sciences, University of the Free State, Bloemfontein, South Africa
4. Department of Statistics, University of Pretoria, Pretoria, South Africa
5. School of Mathematical and Statistical Sciences, North-West University, Potchefstroom, South Africa