A-optimal design matrices X=(xij)N×n with xij=-1,0,1

Let K(N,n) denote the set of all N × n matrices X = (Xij) where and Xij = -1.0.1 and N≥ n. Such matrices arise in designs of experiments. Certain results on A-optimal designs are obtained. Small N and n are more important for practical use. A -optimal designs in K (N,.n) are known for N <6 and are given here for N = 6.