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What’s the difference between QC and QA?

Quality Control vs Quality Assurance

When starting in the vast world of quality management systems, one of the first questions I had was related to the differences between quality control and quality assurance. I think these phrases get thrown around interchangeably, and I’m sure in certain situations it really doesn’t matter, but overall I think there are a few distinct differences between the two. As your reading and articles get more sophisticated, it can be valuable to understand both of these terms. Let’s start with some simple definitions.

Quality Control (QC)

Quality control (QC) is a process by which entities review the quality of all factors involved in production. ISO 9000 defines quality control as “A part of quality management focused on fulfilling quality requirements”.[1]

Source: https://en.wikipedia.org/wiki/Quality_control

Quality Assurance (QA)

Quality assurance (QA) is a way of preventing mistakes and defects in manufactured products and avoiding problems when delivering products or services to customers; which ISO 9000 defines as “part of quality management focused on providing confidence that quality requirements will be fulfilled”.[1]

Source: https://en.wikipedia.org/wiki/Quality_assurance

Comparison

Quality requirements is used in both of these definitions. Quality Control is the idea of ensuring that the product you are producing meets all quality requirements. This may be physical checks, documentation reviews, outside service certificates, basically anything that shows that the product you are producing is made to the company’s desired requirements.

Quality Assurance are the policies and procedures in place that set the quality requirements. These are the rules that are put in place to make sure that physical checks are completed, documentation reviews are performed, and outside service certifications are required.

Think of Quality Assurance employees as quality managers and Quality Control employees as quality inspectors. The managers determine what needs to be done and give guidance and tasks to the inspectors. The inspectors carry out the tasks and confirm to their managers that the job was done correctly.

You need quality assurance in place so quality control is successful. If not, what does quality control have to do? Quality Assurance develops the checklist that needs to be completed. Quality Control completes the checklist and turns it in for review.

Example

Below is a very simplified example of the relationship between quality assurance and quality control:

Company A is in the business of making red boxes for their customers. Due to their history of making red boxes, the quality assurance department knows that the customer will not accept the product unless it is colored red and in the shape of a box. To ensure that only red boxes are delivered, quality assurance must find a way to confirm that a red box is being produced consistently.

So the quality assurance department creates a checklist and a policy. The policy states that every time a customer orders a red box, this checklist must be completed and handed to their delivery department before it can be shipped. The checklist is a document to record the results of a quality check. This is spread throughout the company through training and other means.

The next time a red box is ordered, the quality control department knows that a checklist must be completed and given to the delivery department. So they go to the product before delivery and ensure that the product is indeed a red box. They document this on the checklist and keep it as a record. Now that the delivery department has received the completed checklist, there is no doubt that the red box is ready for its customer.

Conclusion

While these two terms are different, they do work hand in hand. Depending on your quality department’s goals and capabilities, an individual can perform the duties of both the assurance side and quality side of their system. This approach could be challenging, but not impossible. There are many benefits in separating the two tasks as much as possible to ensure that a healthy quality management system can thrive.

Overall, as long as you understand that many people in conversation may use the words incorrectly, quality assurance and quality control can be used as a way to describe the documented checks and balances of a product during its lifetime.

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