Factorial design
An efficient design for experiments with two or more factors uses each possible combination of factor levels (called treatments) in the same number of experimental units. The repeat measurements for each treatment are called replicates and the design is called a factorial design.
Like the design on the prevous page, the following experiment is a factorial design for two factors.
Strength of asphaltic concrete
Factorial designs can also be used for experiments involving three or more factors.
Surface treatment and abrasion