Abstract: Resolution has been the most widely used criterion for comparing regular
fractional factorials since it was introduced in 1961 by Box and Hunter. In this paper,
we examine how a generalized resolution criterion can be defined and used for
assessing nonregular fractional factorials, notably Plackett-Burman designs. Our
generalization is intended to capture projection properties, complementing that of
Webb (1964) whose concept of resolution concerns the estimability of lower order effects
under the assumption that higher order effects are negligible. Our generalized
resolution provides a fruitful criterion for ranking different designs while Webb’s
resolution is mainly useful as a classification rule. An additional advantage of our
approach is that the idea leads to a natural generalization of minimum aberration.
Examples are given to illustrate the usefulness of the new criteria.