What is CTQ tree

CTQ tree is a tool to understand the critical customer needs in more detail and in the quantifiable manner by breaking it down into drivers and requirements.

As shown in the example above, you don’t have to follow an equal pattern for drivers and requirements. Some customer needs will have more drivers than others; some drivers will have more requirements.

Steps to create the CTQ

You may follow the steps below to create a CTQ tree, but there is no hard and fast rules on how it should be created:

• Identify Critical-to-Customer (CTC) Needs

Begin the CTQ tree process by creating a list of needs that are critical to the customer. The CTC may be identified from the Output of the SIPOC diagram depending on the level of details SIPOC is mapped.

• Identify Drivers of Quality

Drivers are the transition point between customer needs and requirements; you don’t necessarily have to be able to measure drivers, but you want them to be a bit more detailed than the broad customer needs you already identified and you want to be flowing in the direction of measurable factors when possible.

In the example provided above, for the Customer Need of “Professional Camera that is suitable for casual traveler“, the drivers are defined based on the understanding of customers needs and areas where improvements can be provided:

• • • Camera body needs to be small and light weight
    • Camera imaging chips need to be high-end
    • Camera lens needs to be multi-purpose

• List Requirements for Each Driver

Requirements are the most detailed breakdown regarding the CTQ. These are the things that you can measure that lead you to understand whether drivers are performing appropriately so customer needs are met.

As shown in the example above, in order for the “Camera body needs to be small and light weight“, the following requirements needs to be met:

• • • Camera’s body weight can’t exceed xxx grams
    • Camera’s body size can’t exceed a x b x c dimension
    • Len’s weight needs to be 80% or lesser than the body

As demonstrated, requirements are usually measured in numbers. These numbers are subsequently used to develop process measurements and metrics for success. 

• Review the CTQ tree

It is important to review the CTQ tree after completing the mapping process. The following questions should be asked to make sure that the CTQ tree is effectively addressing the Customer Needs:

• • • If these requirements are met, will the customer be satisfied?
    • Are these requirements possible in the real world?