In this paper improved class of estimators for estimating 2 y S is proposed adapting  and . We have also extended our study to the case of two phase sampling. The asymptotic expressions for the mean square error and their optimum values have been derived up to the first order of approximation. The theoretical conditions have also been verified by numerical examples. After deep inspection, it has been shown that the proposed estimators are more efficient than usual unbiased estimator, chain ratio estimator and regression estimator.
Singh, Rajesh and Kumar Singh, Viplav
"Improved Class of Estimators for Variance under Single And Two Phase Sampling,"
Journal of Statistics Applications & Probability: Vol. 4
, Article 16.
Available at: https://dc.naturalspublishing.com/jsap/vol4/iss1/16