Estimation of Median in Two-Phase Sampling Using Two Auxiliary Variables

A general family of estimators for estimating the population median is proposed by making use of two auxiliary variables in two-phase sampling. Under simple random sampling without replacement (SRSWOR) scheme, the expressions for bias and mean square error (MSE) of the proposed estimators are given. The minimum MSE of the proposed estimator is equal to the minimum MSE of the Singh et al. (2006) estimator which is more efficient than many of the existing estimators. The proposed estimator, however, has less bias as compared to the Singh et al. (2006) estimator. An efficiency and bias comparison is provided using three data sets.