On the Effect of Stratification When the Two Stratifying Variables Having Bivariate Normal Distribution

Abstract

In this paper, we study the effect of using two stratifying variables on the approximate value of the variance of the stratified sample mean obtained by Al-Kassab and Al-Elemat. We assume that the stratifying variables distributed as bivariate normal. Ten special cases that obtained are applied on the two stratifying variables, by assumption that the two stratifying variables have bivariate normal distribution. A comparison between these special cases is given using bivariate normal distribution.