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Quality Assurance vs Quality Control

Vishwadeep Khatri

Message added by Mayank Gupta

Quality Assurance is a set of activities aiming at improving the process to assure that the output will be defect free. Focus is more on preventing the errors and improving the process


Quality Control is a set of activities aiming at controlling the process output in order to ensure that the output is defect free. Focus is more on audits and quality checks before the output is delivered to the customer


An application-oriented question on the topic along with responses can be seen below. The best answer was provided by Sreyash Sangam on 24th January 2020


Applause for all the respondents - Sreyash Sangam, Nilesh Gham, Keerthi Babu, Deepak Pardasani, Shashikant Adlakha


Also review the answer provided by Mr Venugopal R, Benchmark Six Sigma's in-house expert.


Q 229. "Quality Assurance" and "Quality Control" are often used interchangeably. However, these two terms are not same. Discuss the difference between the two with relevant examples.


Note for website visitors - Two questions are asked every week on this platform. One on Tuesday and the other on Friday.

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Quality Assurance and Quality Control are both important component for the  robust 'Quality Management System'. 


Quality Control (QC) in general is a reactive concept which deals with the intermediate quality parameters of products and process once the activity is performed. e.g, The assembly line in an auto industry have passed certain number of vehicles and than QC Team, based on the agreed and standard set of parameters, does the inspection of the same to check where there are any deviations. In,fact there is a concept in industrial world of TEST - MAKE - INSPECT . So inspection part only comes post the make or manufacturing activity is completed. Another example we can consider is of Pharma industry, Here we have big team of Quality control division, who are  responsible at each stages for checking the conformance to standard of Raw material, Intermediate goods as well as the finished goods. All theses processes involve set of equipment, people and parameters based on standard requirement. Hence the major role of QC function is in ensuring that the standards are adhered to in line with the agreed set of parameters. It is always performed as second check or as the validation of completed process, hence it is reactive.


QA or Quality Assurance on the other hand is a larger umbrella or broader concept which is process oriented and take utmost care on minute details at each step, corrects when the process starts deviating. The Quality assurance does derive the Voice of customer and translate those voices into meaningful, relevant and appropriate set of standard parameters & principles customized to organisation internal set of framework. 


e.g., If the process has been defined and qualified by the operation steam in any organisation, it requires to be validated by Quality assurance team so that once the process becomes full fledged, it does produce the goods or services with intended quality parameters as expected from the customer. 

Of course, in order to do that, QA continuously need feedback from QC on the quality of product, category & type of deviations. This helps the QA to formulate policies, rules, stringent protocol, so that instead of waiting for the final quality of product or services, the process can be made more robust and continuous monitoring can be done for its effectiveness.


In conclusion, both the QC and QA works on continuous feedback loop, wherein based on the reactive approach QC highlights the standard of products/services, eventually gives the feedback to QA, which build a proactive mechanism to ensure process effectiveness.

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Benchmark Six Sigma Expert View by Venugopal R


Let us begin by looking at the dictionary meanings for 'Control' and 'Assurance'


Control means – “to exercise restraint or direction over, to hold in check, curb” For example – ‘he has good control over the car even at high speeds’.


Assurance means – “A positive declaration intended to give confidence; A pledge, A guarantee, surety”.  For example - 'The employer gave an assurance that the salary will be paid on time'.


Now, how do you give an ‘Assurance’ for Quality? What would make a customer accept an assurance as a sustainable promise for Quality? How do we institutionalize the methodology for assurance as a globally acceptable practice?


If we look at the evolution of Quality over past one and half century, we would see that it started with an activity to ensure that the goods passed on to customer get inspected and only the ‘acceptable’ ones are dispatched. I am not sure what the person who did this activity was called during those days, but let’s call him / her as ‘Quality inspector’. As the ‘Quality inspector’ kept doing his / her job, the folks who produced the goods started involving with him / her over a period of time and started working on ways to improve the acceptance rate of the product.


Though this helped in bringing some improvements, may limitations being faced by the people performing production started surfacing – viz. Design limitations, Process limitations, Resource related issues, Budget constraints, Raw material issues and so on. Naturally, the immediate and initial reactions are to put in curbs or controls to avoid passing on defects to the next stage. Such 'Quality Controls' included stage-wise inspections, adjustment of process / equipment settings based on feedback, identifying process parameters that are found to influence product quality and monitoring them – all these necessitated employees of different functions to collaborate and exercise various levels of ‘controls’ for maintaining Quality.


If you read the book on ‘Quality Planning and Analysis’ by Dr. Joseph Juran and Frank Gryna, which was popular from the 1980's onward, you will see how they have expanded the process of Quality Planning as a ‘Company wide’ movement. Juran has also referred Quality as “small q” and the “Big Q”. The “Big Q” defined Quality beyond the boundaries of ‘Product & Processes’ and led to encompassing all functions of the organization. He has been one of the first experts to realize that by mere inspection and control measures, we cannot provide an assurance on a sustained Quality output from an organization. His work has been an enlightenment towards understanding the concept of ‘Quality Assurance’


Some of the topics as part of his reference to company-wide Quality, that built a framework for Quality Assurance include:

1.      Quality Costs,

2.      Strategic Quality Management,

3.      Corporate Quality culture,

4.      Customer needs understanding,

5.      Designing for Quality,

6.      Supply Chain Quality,

7.      Manufacturing Quality,

8.      Process Audits,

9.      Conformance to specifications and fitness for use,

10.  Sampling plans,

11.  Quality Assurance audits and reporting,

12.  Application of Statistical techniques for analysing, controlling and designing for Quality


Soon, during the late 1980's, the concept of an international Quality Management System (QMS) emerged in the form of ISO 9000 series of standards for Quality and stormed the world. Many customers consider such QMS certifications as a substantiation for Quality Assurance.


Holding on to the concept of ‘Big-Q’, the movement further progressed into extending and combining the use of Quality Management tools and methodologies for the overall prospering of the business, giving rise to Business Excellence Models. Thus, Quality Control and Quality Assurance can be seen as stages in the Quality Continuum.


It may also be noted each stage of the continuum would continue to uphold the good practices of the earlier stage. Thus, certain extent of good inspection practices will be part of Quality Control. Quality Control practices will be included in the Quality Assurance System. Quality Assurance systems would be incorporated within any good Business Excellence program.

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Exactly both are different.

Decades ago the industries only had QC as a department. This department was responsible for inspecting defects or errors in the “PRODUCT”. 
However this started costing a lot to the organisations on hiring inspectors, higher lead time etc. 
That is when the Quality Assurance emerged. Now this department is responsible for identifying deviations or errors in the “PROCESS”.  
So QA is a proactive activity where you prevent the defect from happening by attacking in the process itself. 


For example a leading mobile manufacturing company spending lot of time to identify the defects and they are correcting the defects on qc process. So they implement the qa to identity the root cause and based on root cause they idenfity that, there is deviation on process. 


So they fixed the process deviation and prevent the errors.



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Quality Control Quality Assurance
QC is a method that deliberates on fulfilling the standard request. It is a method that deliberates on providing assurance that quality request are achieved.
A QC aim is to spot and improve the defects. A QA aim is to forestall the defect.
QC is a methodology to verify quality. QA is that the technique of managing quality.
QC continually involves Executing the program. QA doesn't involve executing  the set of related measures or activities
Testing team is answerable for QC. All team members are chargeable for QA.
QC means that Action for Executing the planned method. QA means that designing for doing a method.
Statistical Technique used on QC is understood as applied Statistical Quality Control (SPC). Statistical Technique used on QA is understood as Statistical Process Control (SPC)
QC ensures that positive  results of what you've got done are what you expected. QA makes certain you're doing the correct things.
QC ensures that the standards are followed while engaged working on the Product. QA Defines standards and methodologies to followed so as to fulfill the client needs.
QC is  the method to verify that deliverable. QA is that the method to form the deliverable.
QC is accountable for product testing life cycle. QA is chargeable for full Product development life cycle.
QC Example: Validation. QA Example: Verification
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Quality means ensuring that the product  manufactured is defect free or the service rendered to the customer is supreme in nature with no flaws.  Quality assurance (QA) is a way of averting defects  and mistake in manufactured goods and products  and  service availability to the customer. QA  has its applications in various sectors like- software, insurance, banking, medicine, transportation, manufacturing industries etc. 

QA  is a part of quality management of manufacturing and service industry that  boosts confidence  on manufacturers, service providers and end customers, that all  quality requirements are being met with and product/service rendered is defect free. 

The two most commonly used  terms used in quality management systems are: "quality assurance" and "quality control" and are often mistaken for each other and used interchangeably many a times. The  term  quality assurance is used  for example-  as an implementation of  accreditation guidelines of medical hospitals and  laboratories by various external assessors such as  JCI, NABH, CAP, NABL etc. Basically these  guidelines need to be followed by the medical institutes, in order to ensure  the provision of  quality health services to the patients.  Quality control(QC) on the other hand is  a measure of fifth phase of Six sigma model- DMAIC-Define,  measure, analyze, improve, control. Basically DMAIC is a data driven model to ensure quality and improvement.   Control phase  or QC is executed by various control charts and other statistical tools. 

Quality assurance encompasses all the  standardized administrative and  procedural activities that lead to fulfillment of different quality systems leading to error free product and service. Quality control, in contrast, deals with more of process output in terms of  perfect product and / or service. 

Quality assurance banks on two main principles-  "Fit for purpose" (Product/service is fit for intended purpose) and  "right first time"( mistake free product/service). The two principles are used  before developing (engineering) a novel technical product: Engineering is to make the product work at least once, while the quality assurance needs  to make the product  work all the time. 


The various approaches of QA are:


Failure testing /Stress Testing of  a consumer product:


Statistical control of the data of the product:


Total quality management:

Maintaining the quality of product and service in compliance with processes of Quality assurance.


Models and standards:

Various international standards such as ISO 9000, ISO 17025 are in place for determining the international standards and requirements  to carry out various tests and their calibrations. These requirements outline the guidelines for accreditation of laboratories. There are several tools  devised by WHO for accreditation of public health laboratories. 


Examples of QA in various industries:


Medical industry:

QA is an integral part  to identify the standards of various medical equipments  and services. QA is of utmost importance in development of new devices, new pharmaceutical products and  new diagnostic  tests launching.   For example- external agencies like  Atomic energy regulatory board (AERB) govern  the standards for diagnostic radiology

Aerospace industry:

 Here Product assurance(PA) is used many a times, rather than quality assurance. The PA/QA wing works independently for development of defect free products, which are vital for safety to  human life and free of any hazards to the environment. 

Software development:

QA in software industry  refers to various software engineering processes and their monitoring and used to ensure quality. Various models such as Capability maturity model integration (CMMI), ISO 9000 are used for these.


Various quality management system used for QA are:

 Six Sigma, Measurement system analysis, Quality function deployment, Failure mode and effect analysis, Advanced product quality planning(APQP), CMMI etc.


Quality control (QC) is a part of Quality management system (QMS),  focused on  achieving the quality specifications of the product/service. 

Various methods have been proposed to achieve the desirable QC in products or services. 


Statistical Quality Control:  The application of statistical methods like control charts and acceptance sampling to achieve quality control.


Total Quality Control: Connotes  involvement of various departments  in addition to the product designing or the the service department. This includes- marketing, accounting, design, finance, HR, Sales etc.


Statistical Process Control: Includes use of control charts to monitor a process and feedback  given to the unit, responsible for the process.


Lean Six Sigma: Statistical six sigma along with lean tool applications to  reduce variation, eliminate waste and  provide value to the system and organization.


Quality control  is achieved by ensuring markedly reduced or zero defects. Quality control requires  training for  the staff and personals, involved in the process  for  creating  a benchmark  for product/ service quality and reduce statistically significant variation. Quality control of a product/service requires a standard control to be developed and then comparing the control with current product/process.

Understanding Quality Control 

Quality control involves active testing of randomly picked units and evaluating if they pass the desired quality criteria which are specified. The purpose of the testing is to determine any needs for corrective actions in the manufacturing process. Stringent quality control ensures the development of products and services that add value and are customer compliant.

The quality control used in a  real business world  depends on the type of product or industry. 

For example,  in consumer goods like food and drug, quality control  implication lies in ensuring that product ingestion does not lead to any adverse biological reaction in consumers. So QC implies doing chemical and microbiological testing of samples picked randomly from production line, to ensure that product is in compliance with its contents, as stated in the visible package label and product is sterile with no growth of disease-causing microorganisms. 

In  medical laboratories, QC  means inter laboratory testing of same sample,  comparison of  test reports  of a laboratory with a standard accredited lab and to ensure that there is no significant statistical variation of test results.

The Techniques of Quality Control:

There are various methods of checking performance of quality control. One of the most common ways  is a graphic  chart to  check if the product  meets intended  attributes/ specifications. When  the chart  specifically analyses a single attribute of the product it is called a univariate chart. When a chart measures multiple product attributes, it is called a multivariate chart.

A  very common form of a quality control chart is the X-Bar Chart,  used for studying randomly picked up products, where the Y-axis on the chart tracks the degree of variance in the tested attribute and X axis tracks sample tested. The pattern of variance observed, helps in determining the nature of defects, systemic vs Random.

In medical laboratories  use of Levey-Jennings chart(LJ Chart)  is commonly employed to check the accuracy of the QC value  run on particular day and to identify the outliers if any and plotting a curve for the QC values obtained throughout the month. The mean  and standard deviations are obtained after running the control daily. A particular day run of QC is rejected, based on 12s  rule(rejection, if control value exceeds  a 2SD control limit) or 1 3S rule(rejection, if control value exceeds a 3SD control limit), depending on the guidelines followed by laboratory according to accreditation norms.





The Taguchi Method of quality control emphasizes on research and development, product design and development in reduction of defects in products. It says that engineering and designing of product is much more important than standard manufacturing process of the product.

Inspection by Quality Control Inspectors 

Quality control inspectors   try to ensure  a defect  free product/ service to the consumers. They try to evaluate the products/services by  practical testing. They can fix the issue themselves or inform the process supervisors for remedial actions and if still not corrected, then  reject the product/service.





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The chosen best answer is that of Sreyash Sangam for succinctly outlining the differences between the two terms. Deepak Pardasani's answer provides a simple point by point comparison making the concept easy to understand. Shashikant Adlakha provides a detailed view with tools that are associate with both the concepts. 


For Benchmark Expert view, read through the answer provided by Venugopal R. It explains the Quality Continuum in addition to providing differences between the two terms. 

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