2~m(2~l)~1Designs Containing Clear Two-factor Interaction Components

The orthogonal arrays with mixed levels have become widely used in fractional fac-torial designs. It is highly desirable to know when such designs with resolution III or IVhave clear two-factor interaction components (2fc’s).First, this paper gives a complete classifcation of the existence of clear2fc’s inregular2m41designs with resolution III or IV. The necessary and sufcient conditions fora2m41design to have clear2fc’s are given. Then, it gives a complete classifcation of theexistence of clear2fc’s in regular2m81designs with resolution III or IV. The necessaryand sufcient conditions for a2m81design to have clear2fc’s are given.