How to Use a CTQ Tree

One of Six Sigma’s greatest strengths is its focus on the customer. In the Define stage of Six Sigma, project teams work to identify the impact that the specific problem has on the customer. This requires the team to determine the critical to quality (CTQ) customer requirements.

Simply put, CTQs are characteristics that the product or service must have to satisfy the customer. CTQs can include anything from the dimensions of a physical product to the promptness of delivering a service.

What Is a CTQ Tree?

Determining what is most important to customers can be a highly subjective process but the Six Sigma methodology makes it as objective as possible by using the CTQ Tree. This tool helps project teams understand what customers want and how to give it to them.

A CTQ Tree takes the form of a simple diagram that helps project teams identify, list and zero-in on what is most important to the customer. The CTQ tree consists of three components.

1. Need – This is the starting point for understanding how to delight the client. Needs are what your product or service must deliver to customers to make them happy. If you own a pizzeria, your customer’s need is pizza.
2. Driver – These are the elements that your customers will use to judge how well your product or service meets their needs. In the pizzeria example, drivers include the quality of the pizza, the speed with which it is prepared and the variety of available topping choices. Identifying drivers gives project teams another level of understanding about how to satisfy their customers.
3. Requirement – These are measurable performance standards that drivers must meet to satisfy the customer. Requirements help project teams measure the quality and performance of the product or service. In terms of pizza, requirements measure how well the drivers meet the customer needs. Quality is a driver that is measured by appearance, temperature and taste of the pizza. Speed is measured by how quickly the pizza gets to the table, and variety is measured simply by the number of available toppings and combinations.

CTQ Tree Fundamentals

Understanding the fundamentals of the CTQ tree helps teams use it effectively. Teams can create a CTQ tree by following three steps:

• List critical needs – What are the critical needs that your product must meet? Typically, the best way to determine customer needs is to ask customers directly. If this is not an option, customer support staff can provide valuable insight or the team can brainstorm.
• Determine drivers – Look at the process in terms of what’s most important to customers and identify how to meet their needs. Confirm these drivers with customer support and sales staff, or with the customer directly.
• Identify performance requirements – Once the team has identified drivers, the next step is breaking them down into measurable performance requirements. Here, the team takes inventory of the technology and resources to ensure that it can meet client needs.

What do your customers consider critical in your product or service? Creating an effective CTQ tree can help your team understand what the customer truly desires and help you ensure that they get it.