Use a CT tree during a brainstorm session to identify and to organize the inputs that are critical to your customer.

Watch this video to learn more:

Two of the more common CT trees are Critical To (CT) Quality and Critical To (CT) Cost. On a CT tree, the 'Critical To' characteristic is at the top of the tree. Affinities, which are categories, create the second level of the tree. Inputs extend from the affinities.

Example of a CT tree

This CT tree shows what inputs are critical to reduce the number of defects in a manufactured product.

Answers the questions:
  • Who are the customers?
  • What are the key drivers of customer satisfaction?
  • What processes have an impact on the key drivers of customer satisfaction?
  • For a particular project, which customers will be affected and how?
When to Use Purpose
Pre-project Assist in project identification by linking key drivers of customer satisfaction to processes. You can use a CT tree as an input in the Project Prioritization Matrix.
Start of project Improve team and management commitment to the project by showing the links between the project and the customer (can be external or internal), highlighting how the customer will benefit as a result of the project.


  • No project should go forward unless you can identify who it will benefit and why, thus eliminating "pet" projects and projects that do not have merit.
  • Remember, the customer can be internal or external.


  • The CT tree is a team tool. Include customers on the team whenever possible.
  • Determine the primary drivers of customer satisfaction. For example:
    • If you are evaluating critical-to-quality measures, list only the key drivers for quality.
    • If you are evaluating critical-to-cost measures, list only the key drivers for cost.
  • Link the key drivers of customer satisfaction to the process.
  • Record the drivers and links to the process.

Quickly brainstorm ideas in the brainstorming list and click-and-drag them to the diagram to create associations between related ideas. For more information, go to Generate a brainstorm list.

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