Glossary Decisions & governance
What is a Pugh matrix?
A Pugh matrix compares design concepts with a chosen baseline, criterion by criterion, marking each as better, worse or the same.
Also called Pugh method, Pugh concept selection.
Pugh matrix
A Pugh matrix is a concept-selection method developed by Stuart Pugh. Alternatives are listed against criteria and compared with one baseline concept: on each criterion, each is marked better (+), worse (−) or the same (S), and the marks are totalled. It is meant to be repeated, combining the strengths of the better concepts into new ones, rather than to produce a final score.
Why it matters
It suits early design, when there are several concepts and little data. Comparing with a baseline asks only whether each concept is better or worse, a judgment engineers can make before detailed analysis exists.
How it goes wrong
- Treating the totals as an objective answer instead of a structured judgment
- Marking concepts without writing down the assumptions behind each mark
- Comparing against a weak baseline, which makes every alternative look good
In Cairn
Cairn has no Pugh matrix tool and does not score alternatives. The Dendritic lens records the result of a selection: for each node with parts, what was chosen, the alternatives set aside, why each lost and the first principle that decided it. If you run a Pugh matrix elsewhere, record its conclusion in the Dendritic lens, next to the part it decided.
Questions
- Is a Pugh matrix quantitative?
- Only loosely. The marks are relative judgments against a baseline, so its value lies in the criteria and reasons it makes explicit, not in the totals.
- How is a Pugh matrix different from a weighted decision matrix?
- A weighted decision matrix scores each option on a scale and multiplies the scores by criterion weights. A Pugh matrix compares each option with a baseline, usually without weights.
See it on your own system.
Describe what you are building and Cairn interviews you, then builds the first model with you.