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