In a blocked 2k−p design, there are the treatment defining contrast subgroup for defining the fraction and the block defining contrast subgroup for defining the blocking scheme. A main effect or...

In a blocked 2k−p design, there are the treatment defining contrast subgroup for

defining the fraction and the block defining contrast subgroup for defining the

blocking scheme. A main effect or two-factor interaction is said to be clear if

it is also not aliased with any other main effects or two-factor interactions as

well as not confounded with any block effects and strongly clear if it is also

not aliased with any three-factor interactions. A blocked 2k−p design with more

clear effects is considered to be better. Optimal blocked designs according to

this and related criteria are given in Appendix 5B.