A NEW UPPER BOUND FOR THE EFFICIENCY FACTOR OF A BLOCK DESIGN

Abstract

Summary An upper bound for the efficiency factor of a block design, which in many cases is tighter than those reported by other authors, is derived. The bound is based on a lower bound for E(1/ X ) in terms of E( X ) and var( X ) for a random variable X on the unit interval. For the special case of resolvable designs, an improved bound is given which also competes with known bounds for resolvable designs in some cases.