In the design
of experiments, the Design
Resolution is a key criteria for selecting
a fractional factorial design:
Resolution
III 
R_{III} 
two factor interactions
are aliased with main effects 
Resolution
IV 
R_{IV} 
two factor interactions
are aliased with other two factor interactions,
but not with main effects. Main effects
are aliased with three factor interactions. 
Resolution
5 
R_{V} 
two factor interactions
are not aliased with each other, but
are aliased with three factor interaction 
An R_{III} design would usually be used for
screening experiments. There would rarely
be any point in going beyond an R_{V}
design.
In general the resolution is the length
of the shortest word in the defining
relationship.
