House of quality

You fill in the house of quality matrix in a predetermined order. As you do this, a picture emerges of how you need to plan the product (or service). Since all departments collaborate on the matrix, conflicts are avoided when the time comes to implement the plan.

Our example illustrates the development process for a food processor and starts with an empty house of quality.

You start by focusing on the left side of the house of quality. This step involves the marketing team. You list all customer requirements that are relevant to the product. Conducting a survey is one way of finding out what customers want. You can also use other methods such as market analyses to determine requirements because even potential customers often don’t have a clear picture of what they need from a product. The list of customer needs is often referred to as the “what” versus the “how” of technical requirements.

In our example, we want the food processor to have a wide range of features, a modern design, and long-lasting quality. We enter this information in the list. The order isn’t important.

You assign ratings from 1 to 5 (the more important the aspect, the higher the number) right next to the list of customer requirements. You can also create your own scale if it makes more sense for the product and the team. You can solicit the information you need for classifying requirements by conducting customer surveys or communicating with customers. You can then figure out which requirements you should focus on in the planning process.

In our example, the range of functions is most important for customers. The other two requirements were ranked lower.

In the third step, you determine how your planned product compares to competing products. A carefully chosen, representative group of customers compares your product with leading products on the market (or with several competing products). Only one aspect of the customer requirements is compared at a time. In our example, the group of customers would assess how the functionality of the new product compares to the range of functions of competing products.

Once again, you can rate them on a scale of 1 to 5. A rating of 3 equals an equivalent product. Anything below 3 means that your product performs worse than the competing product in terms of the aspect being compared. A higher value means that your product is better received by potential customers. The table for this is located at the right edge of the house of quality. For better visualization, you can connect the individual points to create a graph. You can use different colors for better clarity when comparing your product to several competing products on the market.

While the first three steps primarily reflect the customer’s view and concern marketing, the fourth step requires input from engineers or product designers. Now the question is how exactly to implement the customer requirements. What steps are needed to create an appealing product? Examples include features such as motor power, blade systems, housing design, and controls. You assign this list to the top of the house.

This step requires technical expertise. Now you determine the extent to which the actual state of the product attributes must be adapted to the target state that you derived from the customer requirements. You use three symbols to indicate this:

• Up arrow: The attribute has to be increased in order to optimize it
• Down arrow: The attribute has to be decreased in order to optimize it
• Circle: A target value is desired

In our example, we would expand the blade systems to achieve a wider range of functions. The motor power, on the other hand, already has the target value and is therefore marked with a circle. We would use a down arrow if the customer wanted the product to be cheaper, for example. In other words, the value of this attribute must be decreased.

In our example, we can see that the relationship between the blade system and the range of functions is very strong, and so is given a score of 9. Other relationships (such as the relationship between the range of functions and the housing design) are weak or non-existent.

You can determine the importance of each product attribute by multiplying the values specified in step 6 with the weight specified in step 2 and then adding all the values. You now have an overview of the importance of each feature because you’ve already defined how closely each feature relates to customer requirements. This will help you with further product development. Enter the sum of each column in the bottom row of the matrix to build the foundation of your house of quality.

Experience shows that it’s helpful to specify a relative value in addition to the absolute value. In this case, you record a percentage, meaning you offset the possible maximum value against the actual result.

In our example, we would multiply the value 5 for the motor power by weight 5 (25). Next, multiply the value 5 by the weight 3 (15). Then add the two values to the absolute value (40). Since the maximum value in our example is 145, the resulting values in the graphic below show the relative importance of motor power, blade systems, housing design, and controls:

You can fit another market analysis from the point of view of the product developers in the lower part of the house of quality (the basement). Just like in step 3, engineers compare their product (possibly still in planning) with the competing products on the market. However, the engineers now compare each individual product attribute and evaluate its performance compared to competing products. Just like the evaluation from the customer’s perspective, you assign ratings from 1 to 5 and connect the markings to form a graph.

In the final step, you can start planning. Enter specific data for your target values. In our example, the blade system needs to be extended to 10 functions to meet the requirements.