Fractional Factorial Design
A deliberately chosen fraction of the full factorial — fewer runs, at the cost of effect aliasing governed by design resolution.
Also known as: fractional factorial, 2^(k-p) design
A fractional factorial design (2ᵏ⁻ᵖ) contains only a fraction (half, quarter, eighth …) of the runs of the full factorial. It is the efficient choice for 5 or more factors and for screening phases where higher-order interactions can safely be assumed negligible.
- Half fraction (2ᵏ⁻¹) — halves the runs; often usable at resolution ≥ IV
- Quarter fraction (2ᵏ⁻²) — only a quarter; requires careful generator choice
- Screening fractions such as 2ᴵᴵᴵ⁷⁻⁴ with only 8 runs for 7 factors
See also
Used in
In the Algorithm Lab
Sources
- Montgomery, D. C. — Design and Analysis of Experiments, 10th Edition, Chapter 8
- Box, Hunter & Hunter — Statistics for Experimenters, 2nd Edition, Chapter 6