Escaped Defects
Escaped defects are bugs discovered in production, after release, that testing failed to catch beforehand. Tracking this count and its trend over time is one of the clearest, most outcome-focused signals of whether a testing process is actually working, since it measures real-world impact, not just testing activity.
Unlike most testing metrics, which measure activity or process, escaped defects measure the actual result users experience — a low escaped defect count is meaningful evidence testing is working, regardless of how many test cases were executed or what the code coverage percentage says.
Analyzing escaped defects individually, not just counting them, is often the most valuable part — for each one, understanding why it wasn't caught (a coverage gap, a skipped test type, an environment difference from production) directly informs what to actually change in the testing process going forward.
