Dr. K N S Yadava has a teaching and research experience of about 28 years. He has been awarded the Post Doctoral Fellowship of the Rockefeller Foundation in Population Sciences and worked with Prof J C Caldwell at the Australian National University, Canberra (1986-88). Dr. Kaushalendra Kumar Singh is a lecturer, Department of Statistics, Banaras Hindu University, Varanasi. He has written more than 60 papers for National and International journals of repute. Dr. Singh is recipient of ‘Young Scientist Award’ of Indian Science Congress Association.