Mixed-level fractional factorial split-plot designs containing clear effects.

Mixed-level designs are widely used in the practical experiments. When the levels of some factors are difficult to be changed or controlled, fractional factorial split-plot (FFSP) designs are often used. This paper investigates the sufficient and necessary conditions for a $${2^{(n_{1}+n_{2})-(k_1+k_2)}4_s^{1}}$$ FFSP design with resolution III or IV to have various clear factorial effects, including two types of main effects and three types of two-factor interaction components. The structures of such designs are shown and illustrated with examples. [ABSTRACT FROM AUTHOR]