1. House of Quality Tutorial for Medical Device Design CAPT Kimberly Lewandowski-Walker National Expert, Medical Devices U.S. Food and Drug Administration Office of Regulatory Affairs/ Office of Medical Products and Tobacco Operations

2. What is house of quality?
Methodology to help focus on product or service characteristics from the viewpoints of market-segment, internal, or technology-development needs
Part of quality function deployment (QFD)
Can be cascaded: outputs from one “house” become inputs for a lower- level “house”
Progresses as decisions get closer to engineering/manufacturing details [design outputs, 21 CFR (d)]
Generally starts as a design tool for determination of design inputs [21 CFR (c)]

3. What is house of quality?
Technical requirements
Diagram resembling a house
Basic structure is a table:
Label on left = customer requirements
Across top = technical requirements
Roof is a diagonal matrix of technical requirements vs. technical requirements
Body of house is a matrix of customer requirements vs. technical requirements
Both matrices indicate strength of interactions: strong positive, strong negative, or somewhere between
Additional rooms on right and bottom show product benchmarking and priorities
Benchmarking
Customer
requirements
Priorities

4. Competitive evaluation Customer requirements
QFD template + + _ _ + + _ _ + + _
Technical aspect 1
Technical aspect 2
Technical aspect 3
Technical aspect 4
Technical aspect 5
Technical aspect 6
Technical aspect 7
Technical aspect 8
Technical aspect 9
Technical aspect 10 O ↑ ↓
Requirement 1 5
1.1 +
Requirement 2 9 ●●
Requirement 3 4 ● -
Requirement 4 7
Requirement 5 3
1.2
Requirement 6
Requirement 7 2
2.3
Requirement 8 8
Requirement 9 6
Requirement 10
Technical requirements
Targets
Customer priority
Correlations:
Strong positive
Positive
Strong negative
Negative • + + • _ _
Customer assessment/
Competitive evaluation
Customer requirements • •
Relationships:
Strongest= 10
Strong= 7
Fair= 4
Weak= 1 ●● • ● •
Importance rating
Σ(Priority X relationship)
Technical assessment

5. Customer requirements
What does the customer want from the device?

6. Adhesive bandage example
Customer requirements
Could include
Sticky enough to stick to skin
Not too sticky as to tear skin upon removal
Flexible
Absorbent
Free from bacteria, molds, viruses
Biocompatible

7. Technical requirements Customer requirements
QFD template + + _ _ + + + _ _ + _
Technical aspect 1
Technical aspect 2
Technical aspect 3
Technical aspect 4
Technical aspect 5
Technical aspect 6
Technical aspect 7
Technical aspect 8
Technical aspect 9
Technical aspect 10 O ↑ ↓
Sticky enough to stick to skin 5
1.1 +
Not too sticky 9 ●●
Flexible 4 ● -
Free from microbes 7
Absorbent 3
1.2
Biocompatible
Technical requirements
Targets
Customer priority
Correlations:
Strong positive
Positive
Strong negative
Negative • + + • _ _
Customer assessment/
Competitive evaluation
Customer requirements • •
Relationships:
Strongest= 10
Strong= 7
Fair= 4
Weak= 1 ●● • ●
Σ(Priority X relationship) •
Technical assessment

8. Technical requirements
Form basis of design inputs
Upper “story” of house
Arrows point in direction of desired change

9. Adhesive bandage example
Technical requirements
Woven fabric strip
Biocompatible adhesive
Absorbent pad
Porous polymer coating on pad
Sterile
Breathable materials
Range of sizes
Range of shapes
Sterile barrier for primary packaging
Easy to open primary packaging

10. Adhesive bandage example
Direction of change
Arrow pointing up = increase in the attribute
Arrow pointing down = decrease in the attribute
0 means no change
Woven fabric strip - 0
Biocompatible - 0
Adhesive -
Absorbent pad -
Porous polymer coating on pad - 0
Sterile -

11. Technical requirements Customer requirements
QFD template
Woven plastic strip
Adhesive
Absorbent pad
Polymer coating
Sterile
Breathable
Range of sizes
Range of shapes
Sterile barrier
Easy to open O ↑ o
Sticky enough to stick to skin 5
1.1 +
Not too sticky 9
Flexible 4 -
Free from bacteria 7
Absorbent 3
1.2
Biocompatible
Technical requirements
Targets
Customer priority
Correlations:
Strong positive
Positive
Strong negative
Negative + + _ _
Customer assessment/
Competitive evaluation
Customer requirements
Relationships:
High= 10
Medium= 7
Low= 4
None= 0 ●● ●
Σ(Priority X relationship) •
Technical assessment

12. Competitive benchmarking
Right “wall” of house
Helps quantify customer’s priorities for the different requirements
Compares performance of competing products
Can incorporate a planned satisfaction rating, an improvement factor, and a market leverage factor

13. Customer evaluation
Customer feedback on customer requirements (from left wall of house) on planned device can be obtained using surveys, questionnaires, focus groups, etc.
Customer requirements – can be ranked using 5-point Likert format ranging from “5 - Extremely Important” to “1 - Not Important”

14. Adhesive bandage example
Customer requirements ranked using 5-point Likert format, from “5 - Extremely Important” to “1 - Not Important”
Sticky enough to stick to skin = 5
Not too sticky as to tear skin upon removal = 5
Flexible = 3
Absorbent = 3
Free from bacteria, molds, viruses = 5
Biocompatible = 4

15. Comparison of competing products
Customer feedback solicited comparing planned device to competing devices
Can be compared using 5-point Likert format ranging from “5 – Very Satisfied” to “1 – Very dissatisfied”
Based on customer’s perception of performance

16. Adhesive bandage example
Our bandage
Competitor A’s bandage
Competitor B’s bandage
Sticky enough 4 2 5
Not too sticky
Flexible 3
Absorbent

17. Calculating weight of each customer requirement
Planned satisfaction rating
Determined by design team for the planned device
Improvement factor
Difference between the customer score between the planned device and the planned satisfaction rating, as determined by design team
Difference is multiplied by an improvement factor (e.g., 0.2) plus 1
Sales Point
Can be used to add weight to certain requirements for marketing purposes
Usually 1 to 1.5
Calculation
[Importance * Improvement factor * sales point] = overall weight

18. Adhesive bandage example
Importance
Our bandage
A’s bandage
B’s bandage
Planned rating
Improvement factor
Sales point
Overall weight
Sticky enough 5 4 2
1.2
1.5
9.0
Not too sticky
5.0
Flexible 3
1.1
3.96
Absorbent
1.0
3.0

19. Adhesive bandage example
Overall weight for “sticky enough”
[Importance * improvement factor *sales point]
5 * 1.2 * 1.5 = 9.0

20. Technical characteristics
Forms main body of the House of Quality
Matrix of cells that relate customer requirements (left wall) to technical requirements (upper story)
Each combination of customer and technical requirement is assessed by the design team
Level of interrelationship is determined and a score given by design team
Scores generally are 4-point scale – high, medium, low, none
Scores equate to a numeric value
i.e. “high” = 10
Ie. “medium” = 5
Ie. “low” = 2

21. Adhesive bandage example
Customer requirement = sticky enough
How do technical requirements affect “sticky”?
How does woven fabric strip affect “sticky”?
None = 0
How does adhesive affect “sticky”?
High = 10
How does absorbent pad affect “sticky”?
Medium = 5
Etc.

22. Tech requirement interrelationships
The “roof” of the house
Matrix to identify where the technical requirements support or conflict with each other
Uses the arrows from the technical requirements step
For each cell in the roof matrix, the design team should determine if improving one requirement will cause a negative effect to another requirement
If improving one requirement causes a negative effect to another requirement, but an engineering trade-off is needed or desired, a “-” is put into the cell
If improving one requirement causes another requirement to also improve, a “+” is put into the cell

23. Tech requirements interrelationships
The roof matrix helps the design team determine where an improvement in one technical requirement could lead to improvements in multiple other technical requirements
Also helps alert design team to potential flaws in the design

24. Adhesive bandage example
Technical requirements
Woven fabric strip
Biocompatible adhesive
Absorbent pad
Porous polymer coating on pad
Sterile
How does improving the absorbency of the pad affect the polymer coating of the pad?
“+”, “-”, or “0”?
How does improving the adhesive affect the absorbent pad?

25. Technical priorities The “basement” of the house
Calculated by taking the values for each interrelationship of technical requirement in meeting customer needs (the main body of the house)
Each interrelationship value is multiplied by the overall weighting from the benchmarking “wall” of the house
Values are then summed down the column

26. Adhesive bandage example
Adhesive column (technical requirement)
Sticky enough = 10 * 9 = 90
Not too sticky = 10 * 5 = 50
Flexible = 0 *4 = 0
Free from microbes = 2 * 0 = 0
Absorbent = 0* 3 = 0
Biocompatible = 5 * 0= 0
Sum = 140

27. Adhesive bandage example
Absorbent pad column (technical requirement)
Sticky enough = 2 * 9 = 19
Not too sticky = 5 * 5 = 25
Flexible = 0 *4 = 0
Free from microbes = 2 * 0 = 0
Absorbent = 10* 3 = 30
Biocompatible = 5 * 0= 0
Sum = 74

28. Product targets
Technical benchmarking can be used to compare the technical priorities and planned design inputs to competitor products
Result = design (product) targets

29. Clausing four-phase model
I. Product planning
Determine crucial features based on customer requirements and design concept
II. Design deployment
Compare component characteristics to
design features
III. Manufacturing process planning
Compare process
plans to component characteristics
IV. Production planning
Coordinate operational plans with process plans

30. Clausing four-phase model
“Spins-off” from the initial design house:
Left wall = product (design) targets
Upper story = characteristics of the components
Body of house = component deployment
Result = component targets

31. Clausing four-phase model
New house is formed:
Left wall = component targets
Upper story = key manufacturing operations to produce the components
Body of house = process planning activities
Result = targets for manufacturing processes

32. Clausing four-phase model
New house is formed:
Left wall = manufacturing process targets
Upper story = machine settings
Result = target production settings

33. Technical requirements Customer requirements
QFD template + + _ _ + + + _ _ + _
Woven plastic strip
Adhesive
Absorbent pad
Polymer coating
Sterile
Technical aspect 6
Technical aspect 7
Technical aspect 8
Technical aspect 9
Technical aspect 10 O ↑ o ↓
Sticky enough to stick to skin 5
1.1 +
Not too sticky 9 ●●
Flexible 4 ● -
Free from bacteria 7
Absorbent 3
1.2
Biocompatible
Technical requirements
Targets
Customer priority
Correlations:
Strong positive
Positive
Strong negative
Negative • + + • _ _
Customer assessment/
Competitive evaluation
Customer requirements • •
Relationships:
Strongest= 10
Strong= 7
Fair= 4
Weak= 1 ●● • ●
Σ(Priority X relationship) •
Technical assessment

34. Ready to build your own house?
What new products are you planning to create?
What existing products should you improve?
Get started:
Find more resources at asq.org/learn-about-quality/benchmarking /overview/tutorial-building-house-of-quality.html