Tuesday, August 29, 2006

Quality Assurance Vs Quality Control

There is always a lot of confusion over these two terms and in this article I will try to simplify what they are.

What is Quality Assurance (QA) ?
Quality Assurance are all the activities that go in to defining and managing a process that will assure a certain degree of quality based on the maturity of the process and the applicability of the process. There are two terms here that are important here - one is 'maturity' and the other is 'applicability' and it is important to understand both of them in terms of QA.

Maturity of the process is the degree to which the process is defined. Processes can be vague - eg. Do XYZ activity. Or processes can be well defined - eg. Do XYZ activity using procedure P1 and fill up template T1 and verify it with a checklist C1 by an independent person. Maturity is also dependent on how much the process has been used and fine tuned based on the feedback from using the process. The more it is used and the more feedback incorporated into it the more mature it is. For example the assembly line in a manufacturing plant has a process that is very matured and hence the quality that is assured out of the products that come out of the assembly line is very high. Hence the more a process is used and feedback incorporated to improve it the more mature it becomes.

Applicability of the process to what it is being applied to is also important. Just because the process gave good results in one does not mean it will work everywhere.

What are the activities in quality assurance? This is not a complete list but a representative list of the activities that constitute Quality Assurance.
  • Identifying the goals of the process.
  • Defining the process
  • Applying the process to the various tasks being performed
  • Measuring and analyzing if the process is meeting the goals defined for the process
  • Improving the process by understanding the feedback

What is Quality Control?
Quality Control is one of the elements of the process which attempts to remove the defects in the product during or after it is developed. Quality Control is hence an activity that is performed during or after the product is developed with the only intention of removing the defects that might have got introduced while developing the product. Hence Quality Control is not a process but an activity or set of activities that are done during the process with the aim of removing the defects that got introduced in the process.

The activities that constitute Quality Control are

  • Reviews
  • Testing

As you can see Quality Control is only one of the elements of the process that is defined by Quality Assurance. Quality Assurance takes a holistic view of what is being done. Quality Control is only an activity within the process that attempts to weed out the defects in the product that was produced.

Both Quality Assurance and Quality Control are important. Without a process - developing any product will be futile and no process guarantees a defect free product and hence every product has to be verified and validated by Quality Control.

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