CTQ tree

A CTQ tree, short for critical-to-quality tree, is a diagram used to turn a broad customer requirement into specific characteristics that can be measured. It starts from what the customer says matters, then breaks that need into constituent elements until each one is an actionable, quantitative specification with limits that the product or process must meet. In services, where the offering is not a single object, the decomposition is carried down to the tasks that make it up. Practitioners gather customer views, often by survey, and convert the expressed needs into measurable terms using tools such as design failure mode and effects analysis. The CTQ tree is most often met as part of Six Sigma methodology, where it helps to prioritise requirements so that improvement or design work stays aligned with what the customer actually defines as quality.