Critical to Quality (CTQ) Tree: Explanation and Example

Critical to Quality (CTQ) Tree: Explanation and Example
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Critical to Quality, or CTQ, trees are used to help see the characteristics of a product from a customer point of view. Having one for your business or company will help knowing what your customers are looking for.

CTQ Tree Explanation

An explanation of a CTQ tree is a key measurable aspect of a process or product, which has a specified limit or performance standard that must be met to fully satisfy the customer. In other words, CTQ trees give a visual layout of what a customer expects for a product, what their needs and interests are for that product. The CTQ tree helps in the design production for a product by taking a customers needs into account, adapting the product to what they expect. CTQ trees are used with the Sigma Six methodology processes.

Ways to Make a CTQ Tree

The first step in creating a CTQ tree is to find out what a customer’s functional requirements are for a product. For example, if the project is say a new standard of netbook, perhaps a customer’s requirement is that the netbook be light and small. This first step has a lot of sub-steps, all of which are directly related to what a customer is looking for. Try to identify at least three to five requirements that a customer is looking for.

ctq tree 2

Our example for the netbook may be light and small, able to run high quality graphics (for media playback or video games), a fast processor, high level of customization (such as laptop color or design), and affordable price.

These goals are of course achieved with open dialogue between both the team working on the CTQ as well as the customer. When the requirements are met, then it is time to set measurements for the requirements; that is, that discussion begins on how realistic the requirements are. Can the netbook still be light and small if it has the ability to run quality graphics? Can an affordable price be had if the customer can design their own computer?

The last step is to confirm the requirements that the customers have set for the product and that those requirements can be met by the company or manufacturer. Again, open discussion is advised in order to get to a point where both the customer and the company are happy with the projected ideas and expectations.

The main points a CTQ tree are to make sure that the needs of the customer are met and then converted into a reasonable and detailed project plan for continuation. It also helps the team working on the project get from the idea stage - that of the needs and requirements of the customer - to the planning stage, that is the stage in which the design is put into a more specialization context for the company itself. The time it takes for the completion of a CTQ tree is dependent on when the needs are met and if any more ideas come to the table.

Image Credits:

  1. CTQ Tree 1 at Wikipedia (released into the public domain).
  2. CTQ Tree 2 created by Gina66.