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Quality control: Inspection methods and test equipment used to verify output of a production process. The data is valuable as it provides indication of short and longer term process capability as part of a statistical process control programme. It also provided valuable data post implementation of a change to determine impact and effectiveness.
Quality Assurance: Set of procudures, systmes and processes designed to guarantee a process to give the required outputs as per the product specification. This means that there is no requirement to test the output of the process. Eventually after gaining sufficient data from quality control of processes you can implement QA systems / processes as you will be in a position to determine the neccessary controls based on data and impact of changing certain parameter etc. This is the desired state any company would want to be in and ultimately drives down the cost of quality / poor quality.
There is no short answer that will comprehensively address this basic question, or man y of these questions. Volumes have been written, but Mr. Sahl Huazi has the best answer. Mr. Ezzat, this is a critical question for true quality followers. While you mange a few good points, it is not your strength.
Here is a short answer that may enlighten us all;
QC means "controlling" aspects of production and processing such that the methods and procedures meant to "Assure" quality are invoked and maintained. Control seeks defects, Assurance seeks non-conformities, but both of these are after the fact. Before the events, quality planning requires that controls are identified and assurances are established and these are done as a team, but all insure "Quality" So QA and QC are both required as part of the planning, and the execution(doing, taking action, and checking)
QC is one who inspect the practically and restrict all other employees to follow quality
But QA is mainly concerned about Quality Assuarance providing evidence to consultant or employer in form of documents that contractors or subcontractors are following the QC policy
QA is a set of procedures and system based on specific standards that must be followed in the production phase to get the products or services within these standards.
QC is a set of testing tools used during the execution to correct any deviation from the desired product specifications.
QA & QC both focuses on Quality. QA aims to prevent defects and focuses on process used to make products. QC try to identify defects in the finished product. Verification is an example of QA. Validation/Software Testing is an example of QC. QA-proactive process, QC-reactive process.
Me i will not want to agree with the fact that QA is better that QC or QC is better than QA because the contribution of both of them in a project or quality management system will eventually produce a products or deliverables that will meet customer satisfaction. It is only that one comes after the other. May be i should use this medium to differeciate between the two. By definition, quality assurance is the process of verifying or determining whether product or services meet or exceed customer satisfaction. It has five cycles and they are 'Plan, do, check and act'. Quality assurance team plans on how to produce a product or service that will meet a customer satisfaction at the end of the day. After planning, execution takes place and deliverables are checked for conformity or variance. Any abnormality is then acted upon by the team for correction. Quality control on the other hand is a process employed to ensure a certain level of quality in a product or service. The goal of a quality control team is to identify products or services that do not meet a company’s specified standards of quality. If a problem is identified, the job of a quality control team or professional may involve stopping production or implementation temporarily. Depending on the particular service or product, as well as the type of problem identified, production or implementation may not cease entirely. Simply put, quality assurance ensures a product or service is manufactured, implemented, created, or produced in the right way; while quality control evaluates whether or not the end result is satisfactory.