concept of quality assurance

4.5.1 Why Quality is Important and How Quality May Be Achieved

Objective

To understand the concepts of quality assurance (QA) and quality control (QC), why quality matters to businesses and customers, and the methods and tools used to achieve, maintain and evaluate high quality.

Definition of Quality

Quality is the degree to which a product or service meets customer expectations, statutory requirements and any agreed‑upon standards.

Why Quality Matters

• Customer satisfaction & loyalty – High‑quality products/services meet or exceed expectations, encouraging repeat business.
• Financial performance – Fewer defects reduce waste, re‑work and warranty costs, increasing profit margins.
• Brand reputation & competitive advantage – Quality is a key differentiator in the market.
• Legal & ethical compliance – Conforms to consumer‑rights legislation, health & safety regulations, environmental standards and industry‑specific rules (e.g., CE marking, food‑safety standards).
• Employee morale & productivity – Clear quality standards and training give staff confidence and reduce frustration.

Key Concepts

Quality Assurance (QA)

QA is a systematic, proactive approach that designs and improves processes to prevent defects. It focuses on procedures, documentation, training, supplier management and continuous improvement.

Quality Control (QC)

QC is a reactive, inspection‑based approach that detects defects in finished products or services. It provides immediate feedback that can be fed back into the QA system.

QA vs. QC – Comparison

Aspect	Quality Assurance (QA)	Quality Control (QC)
Purpose	Prevent defects by improving processes.	Detect defects in outputs.
Focus	Processes, procedures, systems.	Products, services, final output.
Typical Activities	Process audits, documentation, training, supplier qualification.	Inspection, testing, sampling, measurement of defect rates.
Timing	During design and throughout production.	At the end of each production run or service delivery.
Outcome	Consistent quality over time.	Immediate identification of non‑conforming items.

Eight‑Step Quality Assurance Process

1. Define quality standards – Identify customer requirements, statutory controls (e.g., consumer‑rights, health & safety) and recognised standards such as ISO 9001.
2. Document the Quality Management System (QMS) – Produce a policy, procedures, work instructions and records; visualise steps with process flowcharts.
3. Train staff – Ensure all employees understand the standards, their role in the process and the importance of quality.
4. Implement process controls – Use checklists, control charts, Statistical Process Control (SPC) and other tools to keep processes within limits.
5. Monitor and measure – Collect data on key performance indicators (KPIs) such as defect rate, cycle time, customer complaints and Cost of Quality.
6. Review and improve – PDCA cycle
   • Plan: set objectives and plan changes.
   • Do: implement changes on a small scale.
   • Check: analyse results (e.g., via control charts).
   • Act: adopt successful changes permanently.
7. Engage suppliers – Include quality clauses in contracts, audit suppliers and share quality data.
8. Promote a quality culture – Communicate quality values, recognise good performance and involve employees in improvement ideas.

Quality Control Activities

• Inspection – Visual or instrument‑based checking of items against specifications.
• Testing – Functional or performance tests (e.g., tensile strength, software debugging).
• Sampling – Selecting a representative batch for inspection (e.g., 1 % random sample).
• Feedback loop – Results are reported to QA teams to trigger process adjustments.

Quality Assurance Tools – Pros & Cons

Tool	Purpose	Advantages	Limitations
Process Flowchart	Map each step of a process.	Clarifies responsibilities; easy to spot bottlenecks.	Time‑consuming to keep up‑to‑date for complex processes.
Control Chart	Monitor variation in a key variable over time.	Detects trends before defects occur; supports SPC.	Requires statistical knowledge; only works for stable processes.
Pareto Analysis	Identify the “vital few” causes of problems.	Focuses improvement effort on biggest impact.	May overlook less frequent but serious issues.
Root‑Cause (Fishbone) Diagram	Analyse underlying reasons for a defect.	Encourages team brainstorming; systematic.	Can become overly detailed; relies on accurate data.
Failure Mode & Effects Analysis (FMEA)	Predict potential failures and their impact.	Proactive risk reduction; useful for new products.	Resource‑intensive; may miss unforeseen failures.
ISO 9001 Audit	Assess conformity with an internationally recognised QMS.	Improves credibility; aligns with legal & market expectations.	Can be costly; may become a “paper exercise” if not linked to improvement.

Cost of Quality (CoQ)

CoQ measures the total cost of ensuring and failing to ensure quality. It is divided into four categories:

Category	What It Covers	Typical Example (small business)
Prevention Costs	Activities that avoid defects (training, process design, supplier qualification).	£2 000 spent on staff training for a new assembly technique.
Appraisal Costs	Inspection and testing to detect defects before delivery.	£1 500 for weekly control‑chart analysis and final‑product inspection.
Internal Failure Costs	Defects found before the product reaches the customer (scrap, re‑work, downtime).	£3 000 spent on re‑working 150 units that failed the in‑process test.
External Failure Costs	Defects discovered after sale (returns, warranty claims, reputation damage).	£4 500 in warranty repairs and replacement costs.

Overall CoQ can be expressed as:

\[ \text{CoQ (\% of production cost)} = \frac{\text{Prevention + Appraisal + Internal Failure + External Failure}}{\text{Total production cost}} \times 100\% \]

Mathematical Representation of Defect Rate

\[ \text{Defect Rate (DR)} = \frac{\text{Number of defective units}}{\text{Total units produced}} \times 100\% \]

Case Study: Reducing Product Returns

1. The firm sets a defect tolerance of 0.5 % (aligned with ISO 9001 requirements).
2. Process flowcharts reveal a bottleneck at the final‑assembly station.
3. Targeted training on the new assembly technique cuts human error.
4. Control charts show a steady decline in defect rate from 0.48 % to 0.22 % over three months.
5. Supplier audits confirm raw‑material quality, further reducing scrap.
6. After six months the return rate falls to 0.2 %, saving £45 000 in warranty costs and boosting profit margin by 1.3 %.

Linking Quality to Other Functional Areas

• Finance – Lower re‑work, scrap and warranty costs reduce variable costs; CoQ analysis quantifies the financial benefit.
• Marketing – Quality is a key brand promise; “high‑quality” claims can justify a price premium and support advertising messages.
• External Influences – Consumer‑rights legislation, health & safety regulations, environmental/ethical standards (e.g., sustainable sourcing) are embedded in a company’s quality policy.
• Human Resources – Training, motivation, performance appraisal and reward systems reinforce a quality‑focused culture.

Summary of Benefits

• Consistent product/service quality → stronger customer trust.
• Reduced waste, re‑work and warranty costs → higher profitability.
• Compliance with legal and industry standards → avoidance of fines and reputational damage.
• Enhanced brand reputation → competitive advantage.
• Continuous‑improvement culture (PDCA) → long‑term sustainability.

When to Use Each Approach

• Quality Assurance – Best when the aim is to embed quality into design and processes (new product development, high‑volume manufacturing).
• Quality Control – Essential where final‑product inspection is required for safety or regulatory reasons (food, pharmaceuticals) or when a quick batch check is needed.
• Both approaches should operate together: QC findings feed into QA improvements, creating a feedback loop.