质量保证与质量控制

Quality assurance and quality control are most important processes for any project, as the project’s success depends on these processes.

Every project has a quality control section to take care of these functions. The quality assurance function usually stays with the organization and the quality control section has to communicate with the organization to coordinate between these two processes.

Since these processes are connected and work in coordination, many professionals, especially those working in small and medium sized organizations, do not understand their differences.

This reminds me of one interaction when I was in my ISO 9001 training course a few years back. I met with many professionals involved in quality management. These people were all from different backgrounds and were working in various fields.

One of the guys I met told me he was working as a QA/QC engineer in his company. I questioned him about his job responsibilities and his duties.

He replied that he walks around and sees if everything is going as planned or not, checks the items for correctness, and he takes propercorrective actionif there are any deviations from the specifications.

I said okay, that takes care of the quality control part of your job, but what about quality assurance?

他不知道他的质量assurance responsibilities.

It often happens that professionals who work as a QA or QC or QA/QC engineer are not aware of their job responsibilities, even though the difference between the responsibilities of quality assurance and quality control functions is clear.

This issue is prevalent in small or medium-sized organizations where they usually do not have the resources to hire QA and QC engineers separately.

在这种情况下，该人可能在QC工作时具有质量保证的标题，有时甚至是质量保证人，甚至更糟。这种歧义不适合该项目，可能会影响可交付的项目的质量以及项目的成功。

Quality assurance is the process of managing the quality of the product. Quality control is used to verify the correctness and quality of the product.Before we start discussing quality assurance and quality control in detail, we have first to understand the term “quality.”

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.”

根据ISO 8402：1996 - 质量管理和质量保证词汇标准，“质量是产品或服务的全部特征和特征，它具有满足既定或暗示需求的能力。”

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 customer’s requirements and that the deliverable being fit for use.

If a product meets or exceeds the customer’s requirements, it is said to be of high quality. However, if it does not meet its stated requirements, the product is of low quality. Please note that, regardless of thegrade, the quality should be high; quality cannot be compromised in any case.

Quality Assurance

The meaning of assurance is surety or trust. Assurance is an act of providing confidence that you can believe in. You can say that quality assurance guarantees the quality of the product. It ensures that the output of the process is defect free and conforms to all requirements.

Quality assurance is a process-based approach; its primary objective is to prevent defects in deliverables in the planning stage to avoid rework, which is always expensive.

这是一个积极主动的过程;它强调planning, documenting, and finalizing the guidelines that will be necessary to assure the quality. It helps to understand the product’s requirements and expectations, and this process starts at the beginning of the project.

Once all requirements and expectations are identified, a plan is developed to meet these requirements and expectations.

Tools Used in the Quality Assurance Process

The following tools are used in quality management: quality audit, process analysis, quality management, and control tools.

In a quality audit, a team of external experts comes in to review the process and procedures. If there are any discrepancies, they will suggest corrective action, and they may suggest an improvement in the process.

Quality audit is a great tool to ensure that the project follows best practices and approved procedures.

In process analysis, you analyze to find any improvements, discover the root cause of any problems and identify any non-value-added activities.

Quality management and control tools include various diagrammatic techniques, which help you find ideas, make decisions, and prioritize issues. A few examples of these tools include an affinity diagram, a tree diagram, network diagram, etc.

Quality Control

Quality control is a product-based approach that concerns the activities and techniques that are used to fulfill the quality requirements.

Quality control functions start right at the beginning of the project work; it is a reactive approach, which helps find defects in deliverables. The primary objective of the quality control process is to make sure that the deliverables are defect free and acceptable and based on the quality requirements.

The quality control process has the following objectives: to find any defects in the product, 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 process can validate the operational process.

For instance, if the project team finds a defect during the execution, they will correct it, and they will send the feedback to the quality assurance team. The quality assurance team will take corrective or preventive action after investigating the cause of this defect to prevent this defect from happening again in the future.

该过程更新后，质量控制人员将遵循更新的过程，以免出现缺陷。

The quality assurance process takes inputs from the quality control process, and vice versa.

Tools Used in the Quality Control Process

Generally, there are three techniques for the quality control process. They are inspection, statistical sampling, and the seven basic tools of quality.

In an inspection, the deliverable is physically examined for any defects and to check 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.

The seven basic tools of quality arescatter diagram,control chart，直方图，清单，Pareto diagram,cause-and-effect analysis, and flowchart. These tools help find defects and the causes of defects.

The Difference Between Quality Assurance and Quality Control

The following are a few differences between the quality assurance and quality control processes:

• Quality assurance focuses on defect prevention, while quality control focuses on defect identification.
• Quality assurance guarantees that the plan was efficient to avoid any anticipated defects. Quality control helps you find defects in the deliverable and correct them.
• Quality assurance is a proactive process which starts even before the work on the deliverable has started, while quality control is a reactive process and its activity starts as soon as you start working on the deliverable.
• Quality assurance is a process-based approach; here you develop the process to create the product, while quality control is a product-based approach where you make sure the product is as per requirements.
• Quality assurance involves processes managing quality, and quality control is used to verify the quality of the product.
• A quality audit is an example of quality assurance while inspection and testing are examples of the quality control process.

Although these processes are different, they complement each other and the output of one is an input of the other.

The Benefits of Quality Assurance and Quality Control

以下是这些过程的一些好处：

• They provide you with high-quality output and eliminate waste.
• They increase the efficiency of operations.
• They provide customer satisfaction, which helps your brand and helps in growing your business.
• Less rework and after-sale support are required, which will help you save a lot of money.
• 他们鼓励高水平的信心和积极进取的团队。

Quality assurance and quality control are closely related, and they have the same objective, i.e., to deliver a defect-free product.

Both processes are an integral part of a quality management plan and failure to apply either of them will result in a low quality product.

Summary

The quality assurance and quality control processes ensure that a product is defect-free and conforms to requirements. Both processes have the same purpose but, the approach is different. Quality assurance is a process-based and quality control is a product-based. Quality assurance designs a process so that the product created by this process is defect free, while quality control checks the product when producing it to prevent a defective product from reaching the market.

These processes play essential roles in the success of your project. Their effectiveness can only be achieved if they are well understood by the organization and the team performing the job.

There is another process, “validate scope,” which might be combined with quality assurance and quality control. I have written another blog post to explain this as well. Please visit:Quality Control and Validate Scope.

Are you involved in quality assurance or quality control activities? If yes, please share your experiences in the comment section.