Optimal bounds on the bias of quasimidranges

摘要

We derive sharp upper and lower bounds on expectations of sample quasimidranges, that is, arithmetic means of two fixed order statistics of the sample, expressed in various scale units. They can be considered as the bounds on the bias of estimating unknown mean of the parent distribution by the above statistics. While determining the appropriate projection, we consider two new auxiliary functions whose usage provides analytical conditions determining the form of corresponding greatest convex minorant. The results are illustrated with numerical examples.