HARTLEY-ROSS UNBIASED ESTIMATOR OF POPULATION MEAN IN RANKED SET SAMPLING USING TWO AUXILIARY VARIABLES
This paper proposed Hartley-Ross (HR) unbiased estimator of the finite population mean using two auxiliary variables in ranked set sampling (RSS). The variance of the proposed unbiased estimator is obtained to first degree of approximation. Comparison among the proposed and some existing estimators are made both theoretically and through simulation study. It is shown that the proposed estimator is more efficient as compared to all other competitor estimators under RSS scheme.
Ranked set sampling; unbiased estimator; efficiency