QFD / House of Quality Walkthrough

Quality Function Deployment (QFD) uses the House of Quality matrix to translate the Voice of Customer (WHATs) into engineering characteristics (HOWs) with measurable targets.

Rooms of the House of Quality

Room	Contents
Left wall	Customer requirements (WHATs) with importance ratings
Ceiling	Technical characteristics (HOWs) — engineering parameters
Relationship matrix (center)	How much each HOW satisfies each WHAT: strong (9), moderate (3), weak (1)
Roof	Correlations between HOWs: positive (+), negative (−), strong/weak
Right wall	Competitive benchmarks — how you compare to competitors on each WHAT
Basement	Technical targets, difficulty, importance scores, competitive benchmarks for HOWs

Column importance score

Importance score for HOW j = Σ (customer importance[i] × relationship weight[i,j]) for all WHATs i Example: WHAT "easy to open" has importance 5. Relationship to "opening force" HOW = strong (9) Contribution = 5 × 9 = 45

CQE exam tips

Four phases of QFD: product planning (HoQ 1), part deployment (HoQ 2), process planning (HoQ 3), production planning (HoQ 4).
A negative roof correlation means improving one HOW hurts another — an engineering trade-off to resolve.
The right wall benchmarks come from the VOC survey (Kano interviews, surveys, focus groups).

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