Improved class of difference-type estimators for population median in survey sampling.

The improved classes of difference-type estimators of finite population median by using auxiliary information in simple random sampling and two-phase sampling have been proposed. The expressions for bias and mean square error are derived up to first order of approximation. Efficiency conditions and numerical comparisons reveal that the proposed class of estimators performs better than the other estimators under same scenario. Using fixed cost the optimum values are obtained for the two-phase sampling scheme. [ABSTRACT FROM AUTHOR]