CONSTRUCTION OF ORTHOGONAL 2-LEVEL DESIGNS OF USER-SPECIFIED RESOLUTION WHERE N-NOT-EQUAL-2(K)

Fractional two-level factorial designs are often used in the early sta ges of an investigation to screen for important factors. Traditionally , 2(n-k) fractional factorial designs of resolution III, IV, or V have been used for this purpose. When the investigator is able to specify the set of nonnegligible factorial effects, it is sometimes possible t o obtain an orthogonal design with fewer runs than a standard textbook design by searching within a wider class of designs called parallel-f lats designs. The run sizes in this class of designs do not necessaril y need to be powers of 2. We discuss an algorithm for constructing ort hogonal parallel-flats designs to meet user specifications. Several ex amples illustrate the use of the algorithm.