1. Institute for Business and Industrial Statistics of the University of Amsterdam (IBIS UvA), Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands
2. King Fahad University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
3. Department of Statistics, Quad-i-Azam University, 45320 Islamabad 44000, Pakistan
4. IBIS UvA, Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands