Continuing our series on Lean Six Sigma, once we have identified an opportunity for an improvement project, we must identify the customer. Who is that customer? The customer is the recipient of the output of the process, product or service being improved by the project.
How do we define critical-to-quality parameters (CTQs)?
First, let us define the term critical to quality (CTQ).
In any product, process or service, a CTQ is a characteristic that meets a key requirement for the customer or the process.
The most important attribute of CTQs is that they are translated directly from the voice of the customer (VOC), giving us a complete picture of customer needs.
If we expressed a CTQ mathematically, it would look like this:
Y=F(x)
Where:
Y = The customer’s CTQ, or what we need to improve using Lean Six Sigma.
F(x) = The internal process or processes that directly affect the customer’s CTQ.
We would read the expression as Y, meaning that the customer’s CTQ is a function of x or the internal processes. Put another way, the customer’s experience is a consequence of our internal processes. Once we know what our internal or external customer wants, we can better understand what needs improvement in our processes, policies, products or services.
Once we establish customer CTQs, the next phases of the Lean Six Sigma project will teach us how to connect them with the internal processes that need improvement.
The diagram below shows three steps that help define customer CTQs:
| 1. Identify All Potential Customers | 2. Capture the Voice of the Customer (VOC) | 3. Identify the Customer’s CTQs |
|---|---|---|
| List all potential customers and segment them appropriately. | Decide what information you need and which tools you will use to gather it. | Organize all customer information and translate it into a specific need.
Identify and prioritize the CTQs for each need. |
References:
Lean Six Sigma by Sheila Shaffie, McGraw Hill.
This article is part of the blog series on the Define phase of a Lean Six Sigma project.
Related reading: How to Define an Improvement Opportunity
This information helped me understand the topic better. Could you explain how a CTQ can be incorporated into a control plan? I am a little confused about that.
Best regards.
Good morning,
A control plan provides an institutional record of a process’s status and how it is defined. It becomes a living document used to sustain process improvements. CT tools, meanwhile, are used by project champions and Black Belts during the Define phase to define DMAIC projects. They provide a way to analyze customer requirements throughout the process and ensure that the organization works on what is truly critical to both itself and the customer, seeking a balance between the two.
The CT matrix identifies customer requirements and visually connects them with the processes that could affect each requirement.
Kind regards