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Solution Selection Matrix and Pugh Matrix

How to compare and select among competing solutions in DMAIC Improve — Pugh matrix, weighted criteria matrix, and the criteria for a good selection method. It sits in Section VII (Improve) of the 2022 CSSBB Body of Knowledge.

Good selection criteria

Agree on criteria (and their weights) before scoring, so the team cannot reverse-engineer a favorite. Typical criteria: effect on the CTQ/Y, cost, time to implement, implementation risk, sustainability, impact on customers and on other processes, and regulatory or safety constraints. Criteria should be independent of one another, or the matrix double-counts. Involve the people who will run the process: they see implementation problems the project team misses.

Pugh matrix (concept selection)

Developed by Stuart Pugh. Pick a datum (often the current process or a leading concept). Rate every other option against the datum on each criterion as + (better), − (worse) or S (same). Count pluses and minuses. The method is unweighted and qualitative; its strength is prompting the team to combine the strengths of several options into a hybrid and run another round.

Criterion	Datum: current process	A: Fixture poka-yoke	B: Retraining	C: New coating pan
Effect on defect rate	D	+	S	+
Cost	D	−	S	−
Time to implement	D	S	S	−
Sustainability	D	+	−	+
Σ+ / Σ−	—	2 / 1	0 / 1	2 / 2

A looks strongest; C's gains come at high cost and delay. A hybrid (A plus a short refresher training) could be added as a new column in a second round.

Weighted criteria matrix

Assign each criterion a weight, score each option on each criterion, multiply and sum. Higher total = better fit with the agreed criteria.

Weights: Effect 40%, Cost 25%, Time 15%, Risk 20% (scores 1–5, 5 = best; illustrative) A Fixture poka-yoke: 5(0.40) + 3(0.25) + 4(0.15) + 4(0.20) = 2.00 + 0.75 + 0.60 + 0.80 = 4.15 B Retraining: 2(0.40) + 5(0.25) + 5(0.15) + 3(0.20) = 0.80 + 1.25 + 0.75 + 0.60 = 3.40 C New coating pan: 5(0.40) + 1(0.25) + 1(0.15) + 3(0.20) = 2.00 + 0.25 + 0.15 + 0.60 = 3.00 → A ranks first. Check sensitivity: does the ranking change if a weight moves by ±5–10 points?

Other inputs to the decision

Cost-benefit or payback analysis for options with significant capital cost.
Risk assessment (e.g. FMEA on the proposed process) for the leading option.
Impact/effort (2×2) matrix to spot quick wins early in screening.

Common exam traps

The matrix supports a decision; it does not make it. Close totals mean the team should discuss, not declare a winner on a 0.05 difference.
Must-have criteria are screens, not weights. A solution that violates a regulatory or safety requirement is eliminated before scoring.
Pugh vs weighted: Pugh compares to a datum with +/−/S and no weights; a weighted matrix scores every option on a scale with weights.
After selection comes risk assessment and a pilot before full rollout.

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More: DMAIC overview · Project charter · VOC & CTQ · SIPOC · MSA in DMAIC · Process capability · Data collection planning · Graphical analysis · Root cause analysis · Multi-vari analysis · Hypothesis testing · Regression · DOE · FMEA · Define tollgate · Change management · Financial benefits · Team dynamics · Improve tollgate · Piloting & scaling · Poka-yoke (BB) · Solution selection · Control plan · SPC in DMAIC · Sustaining gains

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