A main effects screening design is a design with good balance properties as described by a Chisquare criterion. See ChiSquare Efficiency. Such designs have desirable statistical properties for main effect models.
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A measure of the lack of orthogonality evidenced by columns k and l is given by the following expression:
The maximum possible value of χ2, denoted , is obtained. The chisquare efficiency of a design is defined as follows:
Chisquare efficiency indicates how close χ2 is to zero, relative to a design in which pairs of levels show extreme lack of balance.