Critical To Quality (CTQ)

Critical To Quality (CTQ)

Lean Six Sigma relies on the use of Critical to Quality (CTQ) characteristics.  These are the attributes that will be used to measure the success or failure of the project.

When to use

Every Lean Six Sigma project uses CTQs to express the internal and external customer needs that the project will attempt to address.  These CTQs are developed in Define and Measure phases, and then used throughout the project to measure project success.

Instructions

CTQs are the technique used by Lean Six Sigma to express the project requirements.  Critical to Quality is defined as “Critical to Quality, or CTQ is an attribute of a part, assembly, sub-assembly, product, or process that is literally critical to quality or more precisely, has a direct and significant impact on its actual or perceived quality.”

CTQs are derived from internal and external customer needs.  The external customer is normally a buyer or end user of a product or service but does also include out agencies that may levy requirements on a project such as regulatory bodies or government agencies.  The internal customer is usually considered in two categories.  One is the internal business function or unit that is using the result of a business process, such as the payroll process.  These are often called operational CTQs.  The other category includes CTQs that are associated with following the Lean Six Sigma project management methodology or project boundary constraints directed by the project stakeholders.  These could include requirements for how one DMAIC phase of the project is completed and the next phase started.

To identify the CTQs, the Lean Six Sigma team must first identify all the customers of the product or process they are trying to improve. Once the customers have been identified, the Voice of the Customer (VOC) must be captured so that it can be translated into a CTQ. The CTQ that is developed should be validated with the customer to ensure it accurately reflects their need.

Hints & tips

• When listening to the VOC, there will often be gaps in what is needed because the customer does not see the “big picture” of the product or process. These gaps are an indication of the need to identify additional “customers.”
• When there are multiple CTQs, seek to get a prioritization from the customer. The final solution developed by the Lean Six Sigma team may need to compromise one CTQ in order to completely meet another CTQ. Find out from the customer which one is primary.
• When closing out a Lean Six Sigma project, always go back to the original high-level CTQs and demonstrate how the results of the project relate to those CTQs.