A Critical to Quality Tree (CTQ Tree) reflects what the consumers of your process cite as absolutely essential to success. This helps clarify what is considered a defect in the process. It also helps to distinguish what your client’s needs vs what their requirements are.
Use a CTQ tree when you want to investigate your customer base by moving from general needs to more specific ones.
CTQ Tree Steps
- Identify who your clients are.
- Solicit Voice of Client.
- Translate that data into Critical to Client measures. Set ranges and tolerances for the CTCs.
- Determine how well your organization’s process needs to do internally in order to meet those measures.
- Set parameters for your internal processes that deliver to those measures- those are your Critical to Quality measures CTQs.
ASQ Green Belt Critical to Quality Questions
Question: Which of the following tools is used to translate broad requirements into specific requirements?
(A) A quality control plan
(B) The theory of constraints (TOC)
(C) A critical to quality (CTQ) tree
(D) A process flowchart
Answer: A critical to quality tree. This is a definition question. A critical to quality tree takes the voice of the client and translates it into what your organization specifically has to do in order to meet those needs.
A process flowchart maps a process. A quality control plan is a way to mitigate defects, ensure good quality, and avoid the costs incurred by poor quality. The theory of constraints states that your process is limited by its weakest link.