Is it QA or QC? What’s the Difference?
PMBOK® Guide Definition:Quality Assurance (QA): The process of auditing the quality requirements and the results from quality control measurements to ensure the appropriate quality standards and operational definitions are used.
Quality Control (QC): The process of monitoring and recording results of executing the quality activities to assess performance and recommend necessary changes.
Practical Definition:Quality Assurance (QA): The processes of comparing the project activity results against the Quality Plan requirements to determine if the outcomes are within the acceptable quality tolerance ranges and creating the plans to align out-of-spec results within the tolerance ranges.
Quality Control (QC): Monitoring the project work results to determine if they comply with the quality standards set out in the Quality Management Plan.
What is Quality?
Their definition is based on a set of perceptions. I ask for their definition of quality. Most usually shrug and say they can’t describe it but they know quality when they see it. I ask, if you can’t define it, then what is your standard by which to determine if something is of quality when you see it? I am usually met by blank stares.
I lead into the discussion on quality by asking them, “Who makes a higher quality hamburger: McDonald's or Five Guys (a fast-food chain which makes tasty, juicy hamburgers)?” The response is immediate and unanimous usually accompanied by a chuckle: “Five Guys.”
Then I go into a long question and answer period where we discuss the various ingredients and methods of cooking of the hamburgers. Finally, I ask, “When you go to McDonalds, does the hamburger look, smell and taste the same?” They answer yes.
“When you go to Five Guys, do the hamburgers look, smell and taste the same?” They answer, “They taste much better but sometimes the burger is a little bigger or smaller than another location.”
To which I answer, “And therein lies the definition of quality.”
Both companies have a set of procedures, processes, measurements and results, and yet, McDonald's hamburgers are the same no matter where you go, while Five Guys has a greater variance in results.
Quality is about Specification, not the Material UsedQuality is a set of specifications while grade is the characteristics of materials used in developing the project’s deliverables. Quality is planned in advance and documented in a quality plan. The plan is used by both Quality Assurance and Quality Control in determining the project's results adherence to the plan. Grade is specified during the planning processes and the right materials are procured.
McDonald's state their hamburgers are 100% beef. Beef comes from cows. What part of the cow? Any part. So, from which parts of a cow are McDonald’s hamburgers made? The average consumer doesn’t know. Anyone who has had beef in their lives knows there are better cuts of beef and less tasty/desirable cuts of meat.
As stated on their website, Five Guys hamburgers are made from 100% ground chuck meat – a tastier cut of beef resulting in better tasting and more appealing hamburgers. Ground chuck is a higher grade of meat than the beef used for McDonald's burgers.
We often confuse grade with quality. Remember, quality is the degree to which we meet our quality specifications. The higher the quality, the more closely we match our pre-determined, pre-defined specification.
It has nothing to do with the materials something is made of. It is not the taste of the burger. So, in reality, McDonald’s has a higher quality hamburger than Five Guys because the consistency of the overall product is the same no matter where you go. Five Guys has a better tasting burger because they use a higher grade beef. Although I prefer a Five Guys hamburger over McDonald’s, I know the burger is “lower” in quality because there is not as much consistency in one location versus another.
What Says The PMBOK® Guide?The PMBOK® Guide (5th edition) defines three processes concerning quality: Plan Quality Management, Perform Quality Assurance, Control Quality. Note: The PMBOK® Guide is not the quintessential authority on quality. There are more authoritative manuals, but for us project managers, we need to know enough about quality to understand what the various quality folks are doing. The PMBOK® Guide provides the level of information we need.
Plan Quality Management is the process we use to plan not only how we will manage our quality efforts but also define what the quality specifications are. If we are manufacturing ball bearings, we need to specify the size and material. Let’s say the bearings must be round with a diameter of 1 mm plus or minus (±) .02 mm with a rejection rate of less than 0.1%. A bearing will be placed inside of some housing. If the bearing is too big, say 1.03 mm in diameter, it will be too tight in the housing. If it is too small, say 0.97 mm, it will be too loose.
At some point, the ball bearing will have to be measured so only properly sized bearings are sent down the line to be placed in the housing. The rejects are collected and re-processed.
Let’s say we are manufacturing 1000 bearings per hour. The reject rate should be fewer than 1 per hour. If we achieve that, we are meeting our quality specifications.
Quality ControlQuality Control is based on the activities we perform to inspect, measure, weigh and from there we determine if we are meeting the quality specification. QC folks inspect the outcome of our practices to determine if we are in spec. We can do QC on not only the results of our project activities, but our project management practices. Very common inspections for projects are “on-time, on-budget, within scope.”
We use many different methods and tools to determine if our results are outside the specified bounds of our quality plan. We might use run charts, statistical analysis, inspection of results, numerical analysis, Gantt charts, budgeted values versus actual costs, etc. Anything we can measure and have a specification for in the quality plan needs to be monitored for compliance with the plan.
Quality AssurancePerforming Quality Assurance relates to the activities we do to ensure we are meeting our quality specifications and determining the adjustments needed to get us back within the specification’s tolerances. Quality assurance typically follows the cycle popularized by Dr. W. Edward Deming known as the Plan-Do-Check-Act cycle.
In the Plan stage, we determine the course of corrections needed to get our results back in line with the quality specifications.
In the Do stage, we implement our plan of action.
In the Check stage, we look at the results. If we meet our quality specifications, then our plan worked and we move onto the next issue outside our quality boundaries.
In the Act stage, we determine the areas that are still not within our quality specifications and act upon those items following our Plan-Do-Check-Act cycle until we are satisfied our processes, practices, results, etc. are within our quality guidelines.
Quality Assurance personnel take the results found in Quality Control and monitor them for quality compliance and variances. As you can see, Quality Assurance is the bridge between the Quality Planning efforts and the Quality Control results.
ConclusionQuality Control and Quality Assurance are not the same. They are very different functions on our projects. Quality Control (QC) inspects results and reports if the results are within the ranges as specified in the Quality Plan. Quality Assurance is the function that determines how and what adjustments can be made to bring our results into the acceptable tolerances and align with the quality plan.
Meeting the quality plan ensures we meet the customers’ expectations and requirements. According to the PMBOK® Guide, a project that meets or exceeds the stakeholders’ expectations is called successful. And isn’t that what we want as project managers: a successful project?