Defect Leakage
// Definition
The ratio of defects found in production to total defects (production + pre-release). Measures how well testing caught bugs before users did. Lower is better.
// Related terms
Defect Density
Defects per unit of size — typically per thousand lines of code or per function point. Useful for spotting unusually buggy modules and tracking quality trends over time, with the usual caveats about goal-induced metric gaming.
Bug Lifecycle
The stages a defect passes through from discovery to closure: New → Assigned → In Progress → Fixed → Verified → Closed (with possible Reopened, Deferred, or Rejected branches).
UAT (User Acceptance Testing)
Verification by end users or business stakeholders that the system meets their real-world needs. The final validation gate before release.
Learn more · Manual Software Testing
Chapter 7 · Lesson 3: Test Summary Reports and Metrics That Matter