are used in Taguchi
Experimental Designs to help
allocate the appropriate columns of a Taguchi
array to the factors and interactions.
The figures show two alternative linear
graphs for the L8 design:
Column 3 contains the interaction between
columns 1 and 2.
The circles are coded to distinguish the
columns that have many level changes from
those with few changes. If it is difficult
to change the level of one of the factors,
column 1 would be a good choice, and column
4 a poor choice. This would not be a consideration
with classical designs because the runs
but Taguchi experiments are not usually