Many people have trouble understanding the difference between Quality Assurance (QA) and Quality Control (QC) as they are preparing for their Project Management Professional (PMP)® Exam.
That is not surprising. The terms are very closely related and if you don’t work in the field, the difference doesn’t seem too obvious.
And when you look into A Guide to the Project Management Body of Knowledge (PMBOK® Guide) glossary, you'll find that neither Quality Assurance nor Quality Control is defined. Instead, you will only find a definition for the respective processes of Perform Quality Assurance and Control Quality. The PMBOK® Guide is as always a bit dry in its definitions.
Before we “translate” these definitions into everyday words, it is a good idea to remind ourselves of two other quality concepts. They are “Prevention over inspection” and “DIRFT - Do It Right the First Time”. At the heart of these two concepts lies the idea that everything we produce should be produced error free from the start, because it’s more costly to fix an error afterwards.
So... how can we assure that our deliverables are produced error free?
Simple: We have to put appropriate processes in place; processes that are aimed at helping us produce these deliverables without errors every time. But because there will always be some deviation from even the best processes, we also have to put some controls in place, which measure the results after the fact, so that we can make adjustments if necessary.
Quality Assurance therefore encompasses the processes that are aimed at preventing any defects and Quality Control are the measurements we have in place to detect and repair any remaining defects.
So let’s assume that you are manufacturing a new smart phone.
In Quality Assurance you put all the processes in place to ensure that each phone is manufactured defect free. This would include the types of manufacturing equipment used, training people and documenting all production processes.
Quality Control on the other hand comes into play only after the fact, by testing the finished product. For instance you do a sample testing to see if a randomly picked phone from your production line passes or fails the standards.
PMP Exam Sample Questions
Test your understanding of QA / QC with this sample question from the PMP Exam Simulator:
Which of the following project management processes is not included in the Monitoring and Controlling process group?
A) Control Scope
B) Perform Integrated Change Control
C) Control Quality
D) Perform Quality Assurance
Correct Answer: D) Perform Quality Assurance.
Explanation: The Perform Quality Assurance process belongs to the Executing process group.
Reference: A Guide to the Project Management Body of Knowledge, (PMBOK® Guide) - Fifth Edition, page 61