Saturday, October 20, 2018

Quality Control vs Quality Assurance

Quality assurance is the process of managing quality. Quality control is used to verify the correctness and quality of the product.

What is Quality?

The most important and accepted definition of quality is given by Mr. Philip B. Crosby which says quality is “Conformance to requirements.”
According to ISO 8402:1996 (Quality Management and Quality Assurance Vocabulary standard), “Quality is the totality of features and characteristics of a product or service that bears on its ability to satisfy stated or implied needs.”
According to ISO 9000:2000 (Set of International Quality Standards and Guidelines for Quality Management Systems), “Quality is the degree to which a set of inherent (existing) characteristics fulfills requirements.”
Simply put you can say that ‘quality is about meeting the customers’ requirements and the deliverable being fit for use.
If a product meets or exceeds customers’ requirements you can say that the product is of high quality. However, if it is not meeting its stated requirements the product is of low quality.
Keep in mind that, regardless of the grade, the quality should be high. In any case, the quality cannot be compromised.

Quality Assurance

We have discussed the term quality which simply means “fitness to use and conform to requirements.”
What is meant by “assurance?”
Put more simply, it is a surety or trust. This is an act of giving confidence that you can believe in.
You can say that quality assurance assures the quality of the product. This process ensures that the output of the process is defect free and conforms to all stated requirements.
Quality assurance is a process based approach whose prime objective is to prevent defects in deliverable in the planning stage to avoid rework, which costs a lot.
Quality assurance is a proactive process. It emphasizes planning, documenting, and finalizing the guidelines that will be necessary to assure the quality. This process starts at the very beginning of the project to understand the product’s requirements and expectations.
Once all requirements and expectations are identified, a plan is developed to meet these requirements and expectations.

Tools Used in the Quality Assurance Process

There are three tools used in quality management: quality audit, process analysis, quality management, and control tools.
In quality audit, a team of external experts come and review the process and procedures. If they find any discrepancies, they will suggest corrective action. They may also suggest an improvement in the process.
Quality audit is a great tool to ensure that the best practice and approved procedures are being followed.
In process analysis, you analyze the process to find any improvements, discover the root cause of any problem that occurred, and identify any non-value added activities.
Quality management and control tools include various diagrammatic techniques which help you find ideas, help you make decisions, and prioritize issues.
Some examples of quality management and control tools are affinity diagram, tree diagram, network diagram, etc.

Quality Control

Quality assurance is a process based approach; on the other hand, quality control is a product based approach. Quality control is concerned with the operational activities and techniques that are used to fulfill the quality requirements.
Quality control functions start once the project work has begun. It is a reactive approach and helps you find defects in deliverable's.
The objective of the quality control process is to make sure that the deliverable's are defect free and acceptable as per the quality requirements. If the deliverable has a defect, you will take any suitable corrective action.
Simply put, the quality control process has two objectives: to find any defects in the product and correct them, and validate the deliverable.
Quality assurance and quality control are dependent on each other. The quality control process receives input from the quality assurance process, and in turn, gives its feedback to the quality assurance process so that the quality assurance can validate the operational process.
For example, if the project team finds a defect during the project execution, they will correct it and the feedback will be sent to the quality assurance team. The quality assurance people will investigate the cause of this defect and they will take corrective and/or preventive action in the process so this defect will never happen again in the future.
Once the process is updated, the quality control people will follow the process defined by the quality assurance team so the defect does not recur.
The quality assurance process takes input from the quality control process, and the quality control process takes input from the quality assurance process.

Tools Used in the Quality Control Process

Generally, you use three techniques for the quality control process. These techniques are inspection, statistical sampling, and seven basic tools of quality.
In inspection, you physically examine the deliverable for any defects and to see if it matches the requirements.
In statistical sampling, you select a random number of items from a batch and inspect them for any defects and conformance.
Seven basic tools of quality are scatter diagramcontrol chart, histogram, checklist, Pareto diagram, cause and effect analysis, and flow chart. These tools help you find defects and conformance of the product.

The Difference Between Quality Assurance and Quality Control

  • Quality assurance focuses on defect prevention and quality control focuses on defect identification.
  • In quality assurance, you check if the plan was efficient to avoid any anticipated defect. In quality control, you try to find defects and correct them while making the product.
  • Quality assurance is a proactive process while quality control is a reactive process.
  • Quality assurance is a process based approach while quality control is a product based approach.
  • Quality assurance involves processes managing quality, and quality control is used to verify the quality of the product.
  • Quality audit is an example of quality assurance. Inspection and testing are examples of the quality control process.

 The Benefits of Quality Assurance and Quality Control

The following are a few benefits of these processes:
  • They provide you with a high-quality output.
  • They eliminate waste.
  • They increase the efficiency of operations.
  • They provide customer satisfaction, which affects your brand and helps you grow your business.
  • Less rework and after-sale support is required. This will help you save a lot of money.
  • They encourage a high level of confidence and a motivated team.
    Quality assurance and quality control are closely related and their objective is also the same, i.e. to deliver a defect-free product.
Both processes are an integral part of a quality management plan and complement each other. Failing to apply either of them will result in a failure of quality management on the project.


Quality assurance and quality control processes are intended to make a product defect-free and ensure it conforms to requirements. The purpose of both processes is the same, however, the approach is different. Quality assurance is a process based approach. Quality control is a product based approach. Quality assurance designs a process so that the product coming from this process is defect free, while quality control checks the product when you are producing it so no defected product reaches the market.
These processes have important roles in the success of your project. Their effectiveness can only be achieved they are well understood by the organization and the team performing the job.

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