1. School of Mathematics and Statistics, Lanzhou University, Lanzhou 730000, China
2. Department of Statistics, COMSATS University Islamabad, Lahore Campus, Lahore 57000, Pakistan
3. Department of Statistics, Abdul Wali Khan University Mardan, Mardan 23200, Pakistan
4. Department of Quantitative Analysis, College of Business Administration, King Saud University, P.O. Box 71115, Riyadh 11587, Saudi Arabia