--- title: "QA vs QC; types of cost of quality" subject: "Project Engineering" chapter: 4 key: "semester_7/project_engineering:qa-vs-qc-cost-of-quality" source: https://www.bctengineer.com/q/semester_7/project_engineering/qa-vs-qc-cost-of-quality site: BCT Engineering --- # QA vs QC; types of cost of quality Project Engineering · Chapter 4: Project Implementation and Controlling - Asked in: 2081 Baisakh, 2+6 marks; 2080 Baisakh, 8 marks (asked 2 times) - Video: [Explaining the Cost of Quality, the 4 Cost Categories and Juran’s Quality Cost Curve](https://www.youtube.com/watch?v=LA5B5g1kLkM) — CQE Academy - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/project_engineering/qa-vs-qc-cost-of-quality - Whole chapter: https://www.bctengineer.com/md/semester_7/project_engineering/chapter-4 ## Question Differentiate between quality assurance and quality control. Explain the different types of cost associated with 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). ## Answer #### 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). 1. **Prevention cost** (conformance): spent to avoid defects - quality planning, training, better design, procedures, supplier selection. 2. **Appraisal cost** (conformance): spent to find defects - inspection, testing, laboratory, calibration, audits. 3. **Internal failure cost** (non-conformance): defects found before delivery - rework, scrap, re-testing, delay. 4. **External failure cost** (non-conformance): defects found after delivery - repair under warranty, claims, litigation, loss of reputation, compensation. ```text 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. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which pairing is correct? A. QA is testing of concrete cubes; QC is writing procedures B. QA is product oriented and detects defects; QC is process oriented and prevents them C. Both only happen after the work D. QA is process oriented and prevents defects; QC is product oriented and detects and corrects defects Answer: D. QA is about preventing defects through planned process; QC inspects and tests the product. (Key point: QA vs QC nature) 2. Which activity is quality control rather than quality assurance? A. Setting a procedure for concrete mixing B. Testing concrete cubes C. Staff training D. Preparing a quality plan Answer: B. Testing cubes is inspection of the product, i.e. QC. (Key point: QC example) 3. Which costs belong to the cost of conformance? A. Internal and external failure B. Scrap and litigation C. Prevention and appraisal D. Rework and warranty Answer: C. Prevention and appraisal are spent to achieve quality; failure costs are non-conformance. (Key point: Cost groups) 4. A defect found after handover and repaired under warranty is which cost? A. Appraisal cost B. External failure cost C. Prevention cost D. Internal failure cost Answer: B. Defects found after delivery give external failure cost; internal failure is before delivery. (Key point: Internal vs external failure) ## Related in Project Engineering - [Differentiate quality control and assurance](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Aqa-vs-qc-differentiate) — Project Engineering, chapter 4 - [Quality; QA vs QC; site engineer steps](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Aquality-qa-qc-site-engineer-steps) — Project Engineering, chapter 4 - [Quality; QA vs QC; factors in Nepal](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Aquality-qa-qc-nepal-factors) — Project Engineering, chapter 4 - [Monitoring and quality, cost, schedule control](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Amonitoring-quality-cost-schedule-control) — Project Engineering, chapter 4 - [Closed and open control; quality cost](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Aclosed-open-control-quality-cost) — Project Engineering, chapter 4 - [Monitoring vs evaluation; quality control tools](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Amonitoring-vs-evaluation-quality-tools) — Project Engineering, chapter 4 ## Related in other subjects - [QC, QA, TQC and TQM compared](https://www.bctengineer.com/question.md?key=semester_3%2Fmetrology%3Aquality-control-vs-assurance-tqm) — Metrology, chapter 15 - [QA and QC for a successful project](https://www.bctengineer.com/question.md?key=semester_7%2Fict_project_management%3Aqa-qc-successful-project) — ICT Project Management, chapter 10 - [Software quality assurance](https://www.bctengineer.com/question.md?key=semester_5%2Fsoftware_engineering%3Asqa-note) — Software Engineering, chapter 9 - [Quality assurance](https://www.bctengineer.com/question.md?key=semester_7%2Fict_project_management%3Aquality-assurance) — ICT Project Management, chapter 10