FRACTIONAL RESOLUTION AND MINIMUM ABERRATION IN BLOCKED 2(N-K) DESIGNS

Systematic sources of variation can be reduced in fractional factorial experiments by grouping the runs into blocks. This is accomplished th rough the use of blocking factors. The concepts of resolution and mini mum aberration, design optimization criteria ordinarily used to rank u nblocked fractional factorial designs, are extended to such blocked fr actional factorial designs by treating the treatment and blocking fact ors differently in terms of their contribution to ward length in the d efining contrast subgroup. Some limited theoretical results are derive d, and tables of minimum-aberration blocked two-level fractional facto rial designs are presented and considered. The relationship between cl ear effects (effects Chat are estimable when higher-order effects are assumed negligible) and minimum aberration in the presence of blocking is discussed.