Abstract
In a 1974 paper, T. Matsui studied a selection procedure based on rank sums, the ranks being generated within N blocks of observations, and postulated that the slippage configuration is the least favorable configuration for a procedure _??_ he studied. It is demonstrated by a counterexample constructed for specific cases (k=3; n=1, 2) that this postulation is not always true; further, sometimes the slippage configuration maximizes the probability of correct selection.
