A cost of quality system is designed to identify and measure costs related to quality and poor quality, especially the costs caused by nonconformance. In software quality engineering, these costs include internal failure costs such as rework, retesting, defect analysis, scrap, and delays, and external failure costs such as support, warranty work, customer dissatisfaction, patches, and post-release failures. Prevention and appraisal costs are also tracked to understand investment in quality activities. The purpose is not only to budget improvement efforts or identify best practices, although those may result from analysis. It is also broader than general product development cost. The best answer is measuring the cost of nonconformances because poor-quality costs reveal where improvement is economically justified.

================