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Defect Metrics

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15.1🔒Why Defect Metrics MatterMetrics are the language of accountability. Without them, QA is a matter of opinion ("I think the product is ready" vs "I don't think it's…52 words

15.2🔒Defect DensityWhat it measures: The number of defects relative to the size of the software.164 words

15.3🔒Defect Escape RateWhat it measures: The percentage of defects that escape testing and reach production.158 words

15.4🔒Defect Removal Efficiency (DRE)What it measures: The percentage of defects removed before release.59 words

15.5🔒Defect Severity DistributionTrack the distribution of defects by severity over time:9 words

15.6🔒Cost of Quality (CoQ)The cost of quality framework divides quality costs into four categories:136 words

15.7🔒Q&ASelf-Assessment Quiz: Chapter 151. Calculate the defect density given 30 defects in 80 KLOC. 2. If 22 defects were found in testing and 3 in production, what is the escape…64 words

15.8🔒Key Takeaways- Defect density normalizes defect counts by project size for fair comparisons - Defect escape rate is the single most important QA…59 words

15.9🔒Hands-On ExercisesExercise 15.1 (Beginner): Calculate your team's defect escape rate for the last 3 sprints.60 words

15.10🔒Q&AResume phrasing- Tracked and reduced defect escape rate from 12% to 4% over 3 quarters by implementing risk-based test allocation and three amigos…108 words

15.11🔒Q&ACover letter framingI consider defect escape rate the single most important QA effectiveness metric because it directly answers: "How good are we at catching…71 words

15.12🔒Q&AInterview framing"I approach defect metrics by tracking the full lifecycle: defect density shows the rate of bug introduction, escape rate shows testing…96 words

15.13🔒Q&AWhat not to say- "We found 200 bugs this quarter" -- a vanity metric; it does not tell you if those bugs mattered or if worse ones escaped. - "Our defect…99 words

15.14🔒Q&AQuestion 1Prompt: Your defect escape rate has been steady at 10% for 3 quarters. Leadership says testing is not improving. How do you investigate and…203 words

15.15🔒Q&AQuestion 2Prompt: Explain the Cost of Quality framework to a non-technical executive. Why should they care? What a strong answer should cover: - Four…174 words

15.16🔒Q&AQuestion 3Prompt: How do you use defect severity distribution trends to make decisions? What a strong answer should cover: - Total defect count alone…196 words