1. Design and Analysis of Multi-Factored Experiments
Design Resolution
L. M. Lye
DOE Course

2. Design Resolution for Fractional Factorial Designs
The concept of design resolution is a useful way to catalog fractional factorial designs according to the alias patterns they produce.
Designs of resolution III, IV, and V are particularly important.
The definitions of these terms and an example of each follow.
L. M. Lye
DOE Course

3. 1. Resolution III designs
These designs have no main effect aliased with any other main effects, but main effects are aliased with 2-factor interactions and some two-factor interactions may be aliased with each other.
The 23-1 design with I=ABC is a resolution III design or 2III3-1.
It is mainly used for screening.
L. M. Lye
DOE Course

4. 2. Resolution IV designs
These designs have no main effect aliased with any other main effect or two-factor interactions, but two-factor interactions are aliased with each other.
The 24-1 design with I=ABCD is a resolution IV design or 2IV4-1.
It is used mainly for screening.
L. M. Lye
DOE Course

5. 3. Resolution V designs
These designs have no main effect or two factor interaction aliased with any other main effect or two-factor interaction, but two-factor interactions are aliased with three-factor interactions.
A 25-1 design with I=ABCDE is a resolution V design or 2V5-1.
Resolution V or higher designs are commonly used in response surface methodology to limit the number of runs.
L. M. Lye
DOE Course

6. Guide to choice of fractional factorial designs
L. M. Lye
DOE Course

7. Guide (continued)
L. M. Lye
DOE Course

8. Guide (continued)
Resolution V and higher  safe to use (main and two-factor interactions OK)
Resolution IV  think carefully before proceeding (main OK, two factor interactions are aliased with other two factor interactions)
Resolution III  Stop and reconsider (main effects aliased with two-factor interactions).
See design generators for selected designs in the attached table.
L. M. Lye
DOE Course