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Description of the QFD Process

By Ted Squires

Quality Function Deployment (QFD) is a structured, multi-disciplinary technique for product definition that maximizes value to the customer. The application of the QFD process is an art that varies somewhat from practitioner to practitioner, but the graphic on the next page illustrates a typical application of the QFD process. The graphic shows a concept called the QFD House of Quality (HOQ), a device for organizing the flow of thinking and discussion that leads to finished product specifications. The House of Quality is built by a firm's own multi-disciplinary team under guidance from a trained QFD facilitator (preferably a facilitator with both marketing and technical experience).

Given one or more specific objectives (e.g., a narrow focus such as "optimize engine performance" or a more global focus such as "optimize overall passenger comfort"), the QFD process starts with obtaining customer requirements through market research. These research results are inputs into the House of Quality. Below is a discussion of each of the rooms of the House of Quality and how they are built.

The "Whats" Room: Typically there are many customer requirements, but using a technique called affinity diagramming, the team distills these many requirements into the 20 or 30 most important needs. The affinity diagramming process is critical to the success of QFD in that there is vigorous discussion to reach consensus as to what the customers really meant by their comments. This is a powerful technique for reconciling the different interpretations held by marketing, design engineering or field service. The affinity diagramming process usually takes about one to two solid team days to complete, depending on how narrow or global the objective is. The results from the affinity diagramming are placed into the "Whats" room in the HOQ.

The Importance Ratings and Customer Competitive Assessment Rooms: Marketing and /or the market researcher designs the market research so that the team can use the results as inputs to successfully complete the Importance Ratings and Customer Competitive Assessment rooms. These rooms are located on the matrix where benefit rankings and ratings are assembled for analysis. The Importance Rankings provide the team with a prioritization of customer requirements while the Customer Competitive Assessment allows us to spot strengths and weaknesses in both our product and the competition's products.

The "Hows" Room: The next step is the completion of the "Hows" room. In this activity the entire team asks for each "What", "How would we measure product performance which would provide us an indication of customer satisfaction for this specific 'What'?" The team needs to come up with at least one product performance measure, but sometimes the team recognizes that it takes several measures to adequately characterize product performance.

QFD Model


The Relationships Matrix Room: After the "Hows" room has been completed, the team begins to explore the relationships between all "Whats" and all "Hows" as they complete the Relationships Matrix room. During this task the team systematically asks, "What is the relationship between this specific 'how' and this specific 'what'?" "Is there cause and effect between the two?" This is a consensus decision within the group. Based on the group decision, the team assigns a strong, medium, weak or no relationship value to this specific "what/how" pairing. Then the team goes on to the next "what/how" pairing. This process continues until all "what/how" pairings have been reviewed. The technical community begins to assume team leadership in these areas.

The Absolute Score and Relative Score Rooms: Once the Relationships Matrix room has been completed, the team can then move on to the Absolute Score and Relative Score rooms. This is where the team creates a model or hypothesis as to how product performance contributes to customer satisfaction. Based on the Importance Ratings and the Relationship Matrix values, the team calculates the Absolute and Relative Scores. These calculations are the team's best estimate as to which product performance measures ("hows") exert the greatest impact on overall customer satisfaction. Engineering now begins to know where the product has got to measure up strongly in order to beat the competition.

The last three rooms receive the most input from the technical side of the team, but total team involvement is still vital.

The Correlation Matrix Room: There are times in many products where customer requirements translate into physical design elements which conflict with one another; these conflicts are usually reflected in the product "hows". The Correlation Matrix room is used to help resolve these conflicts by highlighting those "hows" which have are share the greatest conflict.

For example, let's say that the "how" called "weight" should be minimized for greatest customer satisfaction. At the same time there might be two other "hows" titled "strength" and "power capacity". The customer has expressed preferences that these be maximized. Based on what we know about physics, there may be a conflict in minimizing "weight" and maximizing "strength" and "power capacity". The analysis that takes place in the Correlation Matrix room systematically forces a technical review for all likely conflicts and then alerts the team to either optimize or eliminate these conflicts or consider design alternatives.

The mechanics of the analysis is to review each and every "how" for possible conflict (or symbiosis) against every other "how". As mentioned in the previous sentence sometimes symbiotic relationships between "hows" do surface in this analysis. This analysis also allows the team to capitalize on those symbiotic situations.


The Technical Competitive Assessment Room: This is the room where engineering applies the measurements identified during the construction of the "Hows" room. "Does our product perform better than the competitive product according to the specific measure that we have identified?" Here is where the team tests the hypothesis created in the Relative Score room. It helps the team to confirm that it has created "hows" that make sense, that really do accurately measure characteristics leading to customer satisfaction.

Analysis in the Technical Competitive Assessment and Customer Competitive Assessment rooms can also help uncover problems in perception. For example, perhaps the customer wants a car that is fast, so your team comes up with the "how" of "elapsed time in the quarter mile". After comparing performance between your car and the competitor's vehicle, you realize that "you blew the doors off the competitor's old crate". However when you look in the Customer Competitive Assessment room, you see that most of the marketplace perceives the competitor's car as being faster. While you might have chosen one of the correct "hows" to measure performance, it is clear that your single "how" does not completely reflect performance needed to make your car appear faster.

The Target Values Room: The last room of Target Values contains the recommended specifications for the product. These specifications will have been well thought out, reflecting customer needs, competitive offerings and any technical trade-off required because of either design or manufacturing constraints.

The House of Quality matrix is often called the phase one matrix. In the QFD process there is also a phase two matrix to translate finished product specifications into attributes of design (architecture, features, materials, geometry, subassemblies and / or component parts) and their appropriate specifications. Sometimes a phase three matrix is used to attributes of design specifications into manufacturing process specifications (temperature, pressure, viscosity, rpm, etc.).


The huge success enjoyed by firms using QFD is balanced by the numerous firms failing to effectively implement it. We have listed several success keys that should enhance the chances of successful implementation:

  1. Management must make it clear that QFD is a priority.
  2. Set clear priorities for QFD activities. Specifically, management needs to allocate resources for and insist on execution of market research and Technical Competitive Assessment.
  3. Make QFD training available, preferably "just-in-time" to use QFD.
  4. Insist that decisions be based upon customer requirements.
  5. Understand the terms used in QFD.
  6. Insist on cross-functional commitment and participation.
  7. Become leaders of QFD rather than managers.

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