A critical to quality tree (also known as the CTQ tree) is a tool used to translate the needs of the customer (voice of the customer) into measurable product and process quality characteristics.

Use: To generate a critical to quality tree, begin by listing the customer’s needs, preferably in the customer’s own words. Then proceed to refine these needs by asking pertinent questions about them until you have arrived at quality characteristics that can be measured (product and/or process).

Six Sigma Terminology