Factorial
designs involve testing several
(n) factors at two levels, high and low.
A Fractional Factorial experiment uses only
a half (2^{n1}), a quarter (2^{n2}),
or some other division by a power of two
of the number of treatments that would be
required for a Full
Factorial Experiment.
A Full Factorial design with 3 factors
(2^{3} design) would require 8 treatments.
The example shows a 2^{31} design,
it requires only 4 treatments:
Treatment 
A 
B 
C

1 
1 
1 
+1 
2 
+1 
1 
1 
3 
1 
+1 
1 
4 
+1 
+1 
+1 
The Fractional Factorial design is created
by aliasing
Factor C with the Interaction AB. This is
a Resolution
III design.
