Critical To Quality Tree (CTQ)


The aim of Critical to Quality Trees is to translate the most important needs on products or services into Requirements and thereby ensure their quality. You break down the broad goals into specific and measurable requirements.

The Quality if a product or service is often defined as the ability to meet the requirements placed on it. These requirements come from Customers, Environmental , legal or consumer regulations.

The CTQ method helps to bring a clear structure to what these requirements are. The method helps you set priorities and so help you manage the Quality.


Originally a tool from the Six Sigma toolbox, CTQ has a wide range of uses nowadays because it is so easy to do – and so effective.

It is always really useful to have a method like this handy to achieve a quick and on-the-mark overview. Especially when you are aiming to achieve a better customer satisfaction, regardless if the customer is external (outside of your business) or internal (within your business, along your value chain).

Overview of the Critical to Quality Tree.

You start by defining the needs that are most critical on your product or service – those that “make your customer happy”. 

For each of these critical needs, you determine a so-called “Driver”. These are the factors or attributes that the customer is likely to evaluate to see if your product or service is matching their needs. 

You then determine the requirements on these Quality Drivers by setting the range of acceptable results that will guarantee that the Driver will meet its goal.

As the final diagram is in the shape of a tree, the needs are represented by the stem of the tree, the Drivers are the branches and the requirements are the twigs on the branches of your Critical to Quality Tree. 

3 Steps to Critical to Quality Tree

Step 1:
Identify the Critical needs

Define exactly which product or service you are going to analyse.

Ask yourself “What is critical for the success of the product or service?”. It is worthwhile to try and brainstorm this in a team of experts.

Try to get the “Voice of the Customer” by asking your customer directly if at all possible. Indeed, check out the opinions of those who work directly with the customer or the customers: Sales personnel, R&D personnel, Customer reps, etc.

This step can be enlightening as it will often occur that what we consider to be important, is simply not the way the customer sees things! They may see other issues to be far more critical to quality. 

Step 2: Identify Quality Drivers

Once you have determined the customer’s needs, you assess what drives the fulfillment of those needs.

By this, I mean those characteristics, attributes, factors or product features that play a key role or critical role in influencing the fulfillment of that need.

Step 3: Specifying the Requirements on the Performance

Now that you have determined the Quality Drives, your aim will be to set up a range of results that will be acceptable in order for the customer to be satisfied.

Evaluate also the ability to deliver on these requirements: are sufficient machines, manpower, materials, methodologies in place (or is further staff training necessary?) or are they reliable enough to ensure results are within this acceptable range??

Does something have to be done to correct this?


Example of a Critical to Quality Tree

In order to simplify matters and to make it generally understandable, we have taken the example of going to a cafè. Who hasn't been to one?

When you go there, you want to be a satisfied customer and this will be influenced by the Quality Drivers

  • Price
  • Coffee on Offer
  • Staff
  • Surroundings

For each of these Drivers, there are clear requirements that need to be met. 

In this way, the owners know that if they fulfill or meet these requirements, they are most likely to achieve Customer Satisfaction. See Diagram. 

Critical To Quality Tree

As I mentioned starting out, this is a simple but effective technique, applicable to virtually any situation and therefore we wanted to provide you with this information. 

The CTQ Tree is an effective and easy method to just get an overview of the situation with the Customer on the right footing. The CTQ Tree is also beneficial in Project work when you are trying to Solve Problems that are occurring at the interface to the customer, so do try it out, it could be critical! 

Best wishes


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