Improving mean estimation in ranked set sampling using the Rao regression-type estimator

Ranked set sampling is a statistical technique usually used when measuring the variable of interest may be difficult or expensive, but it can be simple to rank the units according to a cheap sorting criterion. In this paper, we revisit the Rao regression-type estimator in the context of the ranked set sampling. The expression of the minimum mean squared error is given and a comparative study, based on simulated and real data, is carried out to clearly show that the considered estimator outperforms some competitive estimators discussed in the recent literature.