- Asked 2/26
- 2081 Baisakh · 2+6 marks
- 2080 Baisakh · 8 marks
QA vs QC; types of cost of quality
Short answer
QA is process-oriented and prevents defects; QC is product-oriented and detects defects. Cost of quality includes prevention and appraisal (conformance) and internal and external failure (non-conformance).
Differentiate between quality assurance and quality control. Explain the different types of cost associated with quality.
Quality assurance and quality control
| Basis | Quality assurance (QA) | Quality control (QC) |
|---|---|---|
| Meaning | Planned, systematic activities that give confidence that quality requirements will be met | Operational techniques that check the product against standards and find defects |
| Nature | Process oriented | Product oriented |
| Aim | Prevent defects | Detect and correct defects |
| Time | Before and during the work | During and after the work |
| Activities | Quality plan, procedures, audits, training | Inspection, testing, sampling, control charts |
| Responsibility | Whole team and management | Quality control staff and inspectors |
| Example | Setting procedure for concrete mixing | Testing concrete cubes |
Costs associated with quality (cost of quality)
The total cost of quality has two groups: the cost of conformance (money spent to achieve good quality) and the cost of non-conformance (money lost due to poor quality).
- Prevention cost (conformance): spent to avoid defects - quality planning, training, better design, procedures, supplier selection.
- Appraisal cost (conformance): spent to find defects - inspection, testing, laboratory, calibration, audits.
- Internal failure cost (non-conformance): defects found before delivery - rework, scrap, re-testing, delay.
- External failure cost (non-conformance): defects found after delivery - repair under warranty, claims, litigation, loss of reputation, compensation.
Total cost of quality
|-- Cost of conformance
| |-- Prevention
| `-- Appraisal
`-- Cost of non-conformance
|-- Internal failure
`-- External failure
Spending more on prevention and appraisal reduces failure costs; the best level is where the total is lowest.
✓ Answer checked by Claude Opus 5.5 (high effort)
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