Estimation of population mean and median using double robust truncation based ranked set sampling

In this paper,we propose a double robust truncation based ranked set sampling (drtbrss) for estimating population mean and median. it provides unbiased estimator of population mean under symmetric population and its efficiency dominates the efficiency of conventional estimators based on ranked set sampling (rss),truncation based rank set sampling (tbrss) and simple random sampling (srs). monte carlo simulation,based on perfect ranking and ranking based on auxiliary variable,is used under symmetric and asymmetric distributions to evaluate effectiveness of the proposed sampling method. further,a real data set is used to illustrate the proposed sampling design.