Cost of Quality (COQ)
Cost of Quality (COQ) is the total cost incurred over the life of a product by investing in preventing nonconformance, appraising deliverables for conformance, and dealing with failure when requirements are not met.
Explanation
Cost of Quality is a comprehensive framework that accounts for all costs related to quality throughout the product lifecycle. It is divided into two main categories: the cost of conformance (money spent to avoid failures) and the cost of nonconformance (money spent because of failures). Together, these categories represent the total investment in quality.\n\nThe cost of conformance includes prevention costs such as training, process documentation, proper equipment, and design reviews, as well as appraisal costs such as testing, inspection, and quality audits. The cost of nonconformance includes internal failure costs like rework, scrap, and retesting, and external failure costs like warranty claims, liability, and lost business.\n\nThe goal of COQ analysis is to find the optimal investment in prevention and appraisal that minimizes total quality costs. Spending more on prevention typically reduces failure costs by a greater amount, resulting in lower total COQ. This analysis supports the PMI principle that quality should be planned in and that prevention is less expensive than dealing with defects.
Key Points
- •Total COQ = cost of conformance + cost of nonconformance
- •Investing in prevention reduces overall quality costs
- •External failure costs are typically the most expensive category
- •COQ analysis helps justify quality improvement investments
Exam Tip
Know the two main categories (conformance and nonconformance) and their subcategories. The exam may ask you to classify specific costs into the correct category.
Frequently Asked Questions
Related Topics
Cost of Conformance
Cost of conformance is the money spent during the project to avoid failures, including prevention costs (building a quality product) and appraisal costs (assessing the quality).
Cost of Nonconformance
Cost of nonconformance is the money spent during and after the project because of failures, including internal failure costs (defects found by the project) and external failure costs (defects found by the customer).
Prevention vs Inspection
Prevention keeps errors out of the process by designing quality into the work, while inspection keeps errors out of the hands of the customer by examining deliverables after they are produced.
Plan Quality Management
Plan Quality Management is the process of identifying quality requirements and standards for the project and its deliverables, and documenting how the project will demonstrate compliance with those requirements.
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