K M S Yadava teaches Statistics and Mathematical demography at Banaras Hindu University, Varanasi, India. He received his M.Sc and Ph.Din statistics from Banaras Hindu University. He is a member of several professional organisations, he is the author of four books. Surendra S Yadava teaches Social statistics and social demography at the Universityof Northern lowa , Cedar Falls, lowa, U.S.A. He received his M.Sc in Statistics from Panjab Agricultural University, India and Ph.D. in Sociology from the Michigan State University, U.S.A.