CTQ tree

A CTQ tree (Critical-to-quality tree) is used to decompose broad customer requirements into more easily quantified requirements. CTQ Trees are often used in the Six Sigma methodology.

Creating a CTQ tree

A CTQ tree decomposes a general, hard to measure requirement on the left, through several steps, into more specific, easy to measure variables on the right. It can be a simple, useful tool when the customer requirements are unspecified, broad, or difficult to measure. Sometimes this decomposition can be via mathematically combinable numbers (profit decomposed into price and cost), but sometimes the variables cannot be directly combined mathematically (customer service decomposed into short wait and friendly staff). A CTQ tree is a quick tool generally used near the beginning of a project, with a focus of discovering measurable critical-to-quality requirements, and not fully exploring the causes that influence those measures. It should not be confused with the Cause-and-Effects diagram, sometimes referred to as the fishbone or Ishikawa diagram.

ee also

*Six Sigma

References

* Rath & Strong Management Consultants, "Six Sigma Pocket Guide", p. 18. ISBN 0-9705079-0-9
* George, Michael L., "Lean Six Sigma", p. 111. ISBN 0-07-138521-5
* iSixSigma.com [http://www.isixsigma.com/library/content/c040913a.asp "Turning Customer Data into Critical to Satisfaction Data"]