| In
experimental design
when two interactions, or a main effect
and an
interaction, share the same
column, and so cannot be individually analyzed
then their effects are aliased.
In the 23-1 design the factor
C is aliased with the interaction AB:
| Treatment |
A |
B |
AB +
C |
| 1 |
-1 |
-1 |
+1 |
| 2 |
+1 |
-1 |
-1 |
| 3 |
-1 |
+1 |
-1 |
| 4 |
+1 |
+1 |
+1 |
When the design is analyzed it is not possible
to distinguish between the effects of changes
in the settings of factor C or the effects
of an interaction between factors A and
C. Thus this design would only be useful
if you believed, from other information,
that interactions between A and C would
not be significant. |
