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Customer Requirement Tree – Critical to Quality Requirements

The Customer Requirements Tree is a Lean tool taught as part of both our Lean Six Sigma Green Belt and our Lean Processes & Tools courses.

It is used to break down hard to measure broad customer requirements into requirements that are easier to measure and control.

The Customer Requirements Tree is also refereed to as the Critical to Quality tree and is a customer focused tool.

Using the tool allows you to define what is expected from the customer based on their broad spoken need. This usually results in upper and lower limits that the customer expects.

In our example below, the need of the customer is a coffee ‘that is good’, but there is no indication what the customer means by ‘good’. The drivers are the factors that generally decide how good a coffee is – taste, temperature and cost. We then assign upper and lower limits for each driver, which are the CTQ requirements - the boundaries the coffee should fall within to be defined as ‘good’.

Customer Requirements Tree

This is a VOC (voice of the customer) tool; defining the customer’s need using easier to measure requirements allows you to adjust the product or service to better suit the customer.

Find out where the Customer Requirements Tree fits into Six Sigma with our DMAIC tools map.

Exercise: Create a Customer Requirements Tree for a product or service that your business provides. Break down the customer need into measurable requirements and see if there is anything you shouldn’t be measuring which you aren’t at the moment.

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