CTQ, or “Critical to Quality,” is a term used in the Six Sigma methodology to identify the features of a product or process, that are most important to the customer. These features are often referred to as “quality characteristics” and are used to define the customer’s requirements for the product or process.

Goal of Six Sigma

In Six Sigma, the goal is to continuously improve processes and eliminate defects, with the ultimate aim of achieving near-perfection (3.4 defects per million opportunities). To do this, it is necessary to identify and prioritise the CTQs for a given process or product, as these are the factors that will have the greatest impact on customer satisfaction.

Identifying CTQ in Six Sigma

There are several ways to identify CTQs. One common method is to conduct a customer survey to gather feedback on the most important aspects of the product or process. This can be done through interviews, focus groups, or online surveys. By gathering input directly from customers, a company can get a clear understanding of what aspects of the product or process are most important to them and what they value most.

Another method for identifying CTQs is to analyse customer complaints or returns. When a customer is dissatisfied with a product or service, they often take the time to provide feedback and share their experience with the company. By analysing this data, it is possible to identify patterns and common themes in customer dissatisfaction. This can be an effective way to identify the root causes of problems and understand what quality characteristics are most critical to customers.

Set Targets for CTQ in Six Sigma

Once the CTQs have been identified, they can be used to set targets for process improvement. For example, if a customer survey reveals that the most important quality characteristic for a particular product is reliability, the Six Sigma team may set a target of reducing the number of failures by a certain percentage. By setting specific, measurable, achievable, relevant, and time-bound (SMART) goals, the team can ensure that their efforts are focused on the areas that will have the greatest impact on customer satisfaction.

To achieve these targets, Six Sigma teams use a variety of tools and techniques, such as data analysis, process mapping, and root cause analysis. These tools help the team to understand the current process, identify the sources of defects and variability, and implement changes to improve the process.

Using the DMAIC Process

One key tool used in Six Sigma is the DMAIC process, which stands for Define, Measure, Analyse, Improve, and Control. This is a structured approach to problem-solving that helps teams to systematically identify and address issues in a process.

Imagine that a company has identified reliability as the most critical quality characteristic for a particular product, based on customer feedback. The Six Sigma team for this product sets a goal of reducing the number of failures by 50% over the next year.

To achieve this goal, the team follows the DMAIC process, starting with the Define phase. They begin by identifying the problem and defining the CTQs. In this case, the problem is the high number of failures and the CTQ is reliability.

Measuring Phase

Next, the team moves on to the measuring phase. They gather data on the current process and assess its performance against the CTQs. This may involve collecting data on process inputs, outputs, and other relevant metrics. For example, they may track the number of failures over time, as well as factors such as the materials used, the manufacturing process, and the conditions under which the product is used.

Analysing Phase

In the analysing phase, the team identifies the root causes of the failures and develops potential solutions. They may use tools such as root cause analysis or process mapping to understand the current process and identify areas for improvement. For example, they may discover that a particular manufacturing step is causing a high number of failures, or that a certain material is prone to failure under certain conditions.

Improve Phase

In the Improve phase, the team implements the solutions and tests their effectiveness. They may make changes to the manufacturing process, switch to a different material, or implement new procedures to prevent failures. Once the solutions have been implemented, the team assesses their impact on the CTQs.

Control Phase

Finally, in the Control phase, the team establishes controls to ensure that the improvements are sustained over time. This may involve implementing new processes or procedures, or installing monitoring systems to track performance. The team may also conduct ongoing assessments to ensure that the CTQs are being met consistently.

By following this process, the Six Sigma team is able to continuously improve the reliability of the product and meet the customer’s expectations for this critical quality characteristic. Over time, this can lead to increased customer satisfaction, improved business performance, and a competitive advantage for the company.