How to Draw A Critical to Quality Tree to offer Better Quality

3/2/2012 Carsten Howitz Project Management

When reviewing a business process we want to make sure that the process produces a product or service of the best possible quality. This is because the quality of the product or service is directly related to customer satisfaction.

So who and what determines what is considered quality? Who is an easy one. The customer ultimately has the final word on what’s quality, not us. If they don’t perceive our products or services as quality, then they are not.

What's Quality?

We need to determine what is critical to the success of the business process and verify it with our customers. In order to do that we can use a tool called Critical-to-Quality (CTQ) tree. It is used to find out our customer’s requirements.

Steps to create a Critical-to-Quality tree

  1. Identify the customer. We need to see if our customers need to be segmented due to different needs.
  2. Identify the customer's need. This becomes the first level of the tree.
  3. Identify the requirements for the need. We usually want to identify at least 2-3 overall requirements. They become the second level of the tree.
  4. Break down the requirements in the second level even further. We can brainstorm or ask our customers to provide feedback to determine this third level of requirements.
  5. Validate the requirements with the customer. Since the customer has the final word on what's considered quality we need their validation of the requirements.

Let me illustrate how to build a CTQ tree. For this example we are reviewing a pizza delivery process.

  1. Our customer can essentially be anyone that likes pizza. There is really no need for segmentation since they all have the same need: A pizza.
  2. As determined in step 1, the customer needs a pizza to be delivered
  3. We can determine a few overall requirements: The quality of the pizza, the delivery speed and the variety of pizzas/toppings we offer
  4. The quality of the pizza can be broken down to: How does it look? How does it taste? How warm is it when they get it?
  5. Now we need to verify these requirements with our customers. We can do this in many different ways, like interviews, surveys, complaints etc.

The resulting tree in a graphical form is shown below.

Critical to Quality Tree

Once we have determined what is Critical to Quality, we can now work on improving the process so we can provide the best possible quality to our customers.


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