Quality Assurance vs Quality Control: Understanding the Difference
Understanding quality assurance vs quality control helps organizations distinguish between activities designed to build confidence in processes and activities used to evaluate whether outputs meet defined requirements.
What Is the Difference Between Quality Assurance and Quality Control?
Quality assurance and quality control are related parts of quality management, but they serve different purposes. Quality assurance is generally concerned with establishing confidence that quality requirements will be fulfilled, while quality control focuses on fulfilling and verifying quality requirements through operational activities.
In practical terms, quality assurance often emphasizes how processes are planned and managed. Quality control commonly emphasizes checking whether products, services or other outputs meet specified criteria.
Organizations normally need both approaches. Reliable processes help prevent problems, while effective control and verification help identify outputs that do not meet requirements.
What Is Quality Assurance?
Quality assurance, often abbreviated as QA, includes planned and systematic activities intended to provide confidence that relevant quality requirements can be fulfilled.
QA commonly focuses on the processes, systems, responsibilities and controls used to produce consistent results. It asks whether the organization has established suitable arrangements for managing work that affects quality.
Quality assurance can include process definition, documented procedures, competency arrangements, internal audits, management review and other activities that support confidence in the quality system.
What Is Quality Control?
Quality control, often abbreviated as QC, includes operational techniques and activities used to fulfill quality requirements.
QC frequently involves checking, measuring, testing, inspecting or otherwise evaluating outputs against defined acceptance criteria.
Quality control helps determine whether a product, service, component, document or other output meets the requirements established for it.
Quality Assurance vs Quality Control at a Glance
The distinction becomes clearer when QA and QC are considered according to their primary focus.
Process Focus
Quality assurance commonly focuses on establishing and maintaining processes capable of producing conforming results.
Output Focus
Quality control commonly focuses on evaluating outputs to determine whether specified requirements have been met.
Complementary Roles
QA and QC support different aspects of quality management and are most effective when connected within the same management system.
Common Quality Assurance Activities
Quality assurance activities depend on the organization and its processes. The objective is generally to establish confidence that appropriate arrangements exist for achieving quality requirements.
Process Design
Defining how important activities should operate and identifying the controls required for consistent results.
Documented Information
Maintaining appropriate procedures, specifications, instructions and records needed to support controlled processes.
Internal Auditing
Evaluating whether management-system arrangements are implemented and functioning as intended.
Common Quality Control Activities
Quality control activities provide evidence about whether defined requirements have been achieved at appropriate stages of work.
Inspection
Examining characteristics of an output and comparing them with defined specifications or acceptance criteria.
Measurement & Testing
Using appropriate methods and equipment to determine whether measurable characteristics meet requirements.
Acceptance Decisions
Using inspection, measurement or testing results to determine whether an output can be accepted, rejected or requires further action.
Quality Assurance Helps Strengthen Processes
One important purpose of quality assurance is to reduce the likelihood that problems will be created by poorly defined or inconsistently managed processes.
This can involve clarifying responsibilities, establishing appropriate methods, ensuring people are competent and making current information available where work is performed.
Preventive process design does not guarantee that every output will conform, but it can create more reliable conditions for achieving consistent quality.
Quality Control Provides Evidence About Outputs
Even well-designed processes may experience variation. Quality control provides methods for evaluating whether the resulting output meets established criteria.
Verification can occur during different stages of production or service delivery rather than only after all work is complete.
Earlier detection can help prevent additional work from being performed on an output that already fails to meet requirements.
How QA and QC Work Together
Quality assurance and quality control should not operate as isolated functions. Information generated through quality control can provide valuable feedback about the effectiveness of processes managed through quality assurance.
For example, repeated defects discovered during inspection may indicate that a process, instruction, equipment condition, supplier control or competency arrangement requires improvement.
Likewise, changes introduced through quality assurance activities should be evaluated to determine whether they improve actual output performance.
QA and QC Within a Quality Management System
A quality management system provides the broader framework in which quality assurance and quality control activities can operate.
The QMS can define responsibilities, processes, documented information, objectives, performance measures, controls and improvement arrangements. QA and QC then contribute to maintaining confidence in those processes and evaluating their outputs.
Treating QA, QC and the QMS as connected elements can provide a more systematic approach than managing individual inspections or procedures independently.
Who Is Responsible for Quality Assurance and Quality Control?
Organizations may assign specialist quality personnel to particular QA and QC activities, but responsibility for quality extends beyond the quality department.
Process owners, managers, supervisors and workers can all influence whether requirements are understood and fulfilled. The exact responsibilities should be defined according to the organization’s structure and activities.
Independent review may be appropriate for some activities, while other quality controls are performed directly within operational processes.
Use QC Findings to Improve QA Processes
When quality control identifies a nonconforming output, immediate action may be needed to control the affected item, service or result.
The organization should also consider whether the finding indicates a wider process problem. Repeated nonconformities can provide evidence that existing controls are not preventing recurrence.
Analysis of quality-control information can therefore contribute directly to process improvement and stronger quality assurance.
Document QA and QC Information Appropriately
Documented information can help establish how quality activities should be performed and provide evidence of completed checks, tests, reviews or other controls.
QA documentation may describe processes, responsibilities and methods. QC records may capture inspection results, measurements, test outcomes, acceptance decisions and identified nonconformities.
Documentation should serve an operational or assurance purpose rather than being created solely to increase the volume of quality records.
Connect Quality Assurance and Quality Control to Improvement
Quality information becomes more valuable when it is used to improve processes. Trends in defects, inspection results, customer feedback and audit findings can help identify recurring weaknesses.
Organizations can use this information to prioritize improvement activities and evaluate whether corrective actions produce better results.
This feedback relationship helps transform QA and QC from separate administrative activities into an integrated quality-management process.
A Simple QA and QC Workflow
Quality assurance and quality control can be connected through a continuous cycle of planning, operation, verification and improvement.
Define
Establish requirements, processes, responsibilities, methods and acceptance criteria for the work.
Perform
Carry out the process under the planned conditions using appropriate resources and controls.
Verify
Inspect, measure, test or otherwise evaluate relevant outputs against defined requirements.
Improve
Use findings and performance information to correct problems and strengthen the processes that produced them.
Common QA and QC Mistakes
Treating QA and QC as Identical
The terms are related but describe different aspects of managing and fulfilling quality requirements.
Relying Only on Inspection
Finding defects after they occur cannot replace effective processes designed to reduce the likelihood of creating them.
Making Quality a Specialist-Only Function
Quality personnel may coordinate important activities, but operational processes throughout the organization affect quality outcomes.
Quality Assurance and Quality Control Are Complementary
The key distinction in quality assurance vs quality control is their primary focus. Quality assurance helps establish confidence in the processes and systems used to achieve quality, while quality control evaluates whether relevant outputs meet defined requirements.
Organizations can achieve a stronger approach to quality when QA and QC are connected through a quality management system and information from both is used for continual improvement.
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