A class of Hartley-Ross type Unbiased estimators for Population Mean using Ranked Set Sampling

In this paper, we propose a class of Hartley-Ross type unbiased estimators for estimating the finite population mean of the study variable under ranked set sampling (RSS), when population mean of the auxiliary variable is known. The variances of the proposed class of unbiased estimators are obtained to first degree of approximation. Both theoretically and numerically, the proposed estimators are compared with some competitor estimators, using three different data sets. It is identified through numerical study that the proposed estimators are more efficient as compared to all other competitor estimators.