© 1996 by Biometrika Trust
MISCELLANEA |
Projective properties of certain orthogonal arrays
Center for Quality and Productivity Improvement, University of Wisconsin-Madison Madison, Wisconsin 53705, U.S.A.
Division of Mathematical Sciences, University of Trondheim N-7034 Trondheim, Norway
A question of importance in factor screening is when a two-level orthogonal design for a multifactor experiment can be projected into lower dimension, typically P = 2 or 3. New results relate to the projectivity P of saturated designs in which n 1 factors are tested in n runs. It is shown that: a design obtained by doubling an n x n orthogonal array is always of projectivity P = 2; a two-level cyclic design is either a factorial array, and hence has P = 2, or it has P = 3; a two-level orthogonal design with 4m runs, m odd, has P = 3. In particular these results allow the designs derived by Plackett & Burman (1946) to be categorised in terms of these projective properties.
Key Words: Design projectivity Design resolution Factor screening Fractional factorial design Orthogonal array Plackett-Burman design