Abstract
Using suitable incomplete block designs with block size three, orthogonally blocked three-level second-order designs are proposed. These designs have reasonably high D-efficiencies and are often much smaller than the existing designs, in terms of block size and/or the total number of points.
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Acknowledgment
The authors thank a referee for his meticulous reading of the earlier versions and for his constructive comments. The work of A. Dey was supported by the Indian National Science Academy under the Senior Scientist program of the Academy. The support is gratefully acknowledged. B. Kole thanks the Indian Statistical Institute, Delhi Center, for providing him with a visiting fellowship.