Classification of Quality Characteristics

The Product & Process Design pillar of the CQE Body of Knowledge is the critical first step in delivering a high quality product that will satisfy your customers.

Delivering a high quality product starts with capturing your customers needs and then translating those needs into Products Features, which are also known as Quality Characteristics.

Quality Characteristics as determined by QFDQuality Characteristics

Your Quality Characteristics are the features about your product that deliver the functional performance that your customers need, want and are willing to pay for.

These are the features about your product that your customers find valuable.

As we learned in the Customer Relations chapter, the best way to translate your customers needs into product features is the use of the Quality Function Deployment tool (House of Quality).

Classification of Quality Characteristics

Once you’ve got your list of Product Features, or Quality Characteristics, it’s time to classify those features.  Wait, aren’t all product features equal in terms of their importance?

No – You’ll have some product features that are way more important than others and by classifying them you’ll be able to isolate & define those features that are critical to quality, safety & performance.

This process takes advantage of the Pareto Principle, which tells us that 80% of your customers satisfaction will be delivered through 20% of your products features.

The Pareto Principle

By going through this process, you will identify those product characteristics that ensure the Safety, Quality, Performance, Functionality & Reliability of your product.

And as a result, you will have established a hierarchy of importance for the various characteristics of the products.

This hierarchy will allow you to strategically focus your resources on the most critical characteristics to ensure customer satisfaction.

Characteristic Categories

Ok – so we’re ready to classify our quality characteristics (product features), how do we do that?

We must define the classification categories that we want to use.

The following categories are generic examples that you can use as a baseline for defining your products categories.

For example, the description below for Critical is based on the potential for injury or harm to the end user.

You can adapt this definition to fit your needs if your product is not likely to result in any sort of injury. Same goes for the other categories.

CriticalA feature whose failure would result in a hazardous or harmful situation for the end user.
MajorA feature whose failure would result in a major reduction in quality (performance, functionality or reliability), but would not likely result in a hazardous situation for your customer.
MinorA feature whose failure would be noticed by the end user but would not significantly impact the users experience (safety, quality, etc).
IncidentalA feature whose failure might go unnoticed by the end user and would not impact safety, quality, performance, functionality, etc.

These Quality Characteristics, and their associated classifications are going used during the design input phase and will be converted to Product Specifications, Process Specifications & Process Controls.


The most important take away from this chapter is the fact that all product features (quality characteristics) are not created equal.

As you move through the design process, you’ll want to focus your attention on the critical features that result in the satisfaction of your customers.

This is accomplished through the classification of quality characteristics.

As we move into the next chapter, Design Input, you’ll get a deeper understanding of how these quality characteristics trickle down into the design of your product and process.

Practice Quiz

Classification of Quality Characteristics

This quiz covers the Classification of Quality Characteristics chapter of the Product & Process Design pillar.