Mix Level Design Contains Pure Effect Conditions

The orthogonal arrays with mixed levels have become widely used in frac-tional factorial designs. Zhao and Zhang (2008) studied the conditions of reso-lution III or IV regular2m4n designs containing clear two-factor interaction com-ponents(2fic’s). This paper studies the necessary and sufficient conditions for a2m4n design to have clear two-factor interaction (containing32fic’s) of a4-level factor and a2-level factor. The necessary and sufficient conditions for a2m4n (n≥2) design to have clear two-factor interaction (containing92fic’s) of two4-level factors are also studied.