IT-01
Bug Ratio Increasing Over Time
Issue Type Distribution
Default severity: medium
Product BacklogMetricsQuality
What it detects
The proportion of Bug/Defect issues relative to total issues in each sprint is increasing across consecutive sprints — rising bug share indicates deteriorating quality, insufficient testing, poor definition of done, or declining technical discipline. This is a leading indicator of cycle time deterioration: bugs consume capacity that should deliver features.
Detection formula
FOR each_sprint S: bug_ratio(S) = COUNT(issues WHERE type IN config.it.bug_types, sprint=S) / COUNT(all_issues, sprint=S) bug_series = \[bug_ratio(S) FOR S in last config.it.trend_window_sprints\] // default: 6 IF linear_regression(bug_series).slope > 0 AND r_squared > config.it.trend_r_squared // default: 0.55 THEN FLAG bug_ratio_increasing IF bug_ratio(latest_sprint) > config.it.critical_bug_ratio // default: 0.30 (30% of sprint = bugs) THEN CRITICAL Report: bug_ratio per sprint as time series; compare across teamsExamples in practice
- A team shows the proportion of bug/defect issues relative to total issues in each sprint is increasing across consecutive sprints while bug types is set to \[\'Bug\',\'Defect\',\'Incident\'\].
- Example signal: The proportion of Bug/Defect issues relative to total issues in each sprint is increasing across consecutive sprints — rising bug share indicates deteriorating quality, insufficient testing, poor definition of done, or declining technical discipline.
Suggested response
Rebalance issue-type mix and debt trends so quality signals stay intentional.
Coaching playbook
Symptom
The proportion of Bug/Defect issues relative to total issues in each sprint is increasing across consecutive sprints — rising bug share indicates deteriorating quality, insufficient testing, poor definition of done, or declining technical discipline. This is a leading indicator of cycle time deterioration: bugs consume capacity that should deliver features.
Why it matters
When "Bug Ratio Increasing Over Time" keeps appearing, the team is signalling a repeatable process gap. Left unexamined, the pattern hides where work really stalls and makes improvement metrics harder to trust.
What you can achieve
Rebalance issue-type mix and debt trends so quality signals stay intentional.
Facilitation questions
- What system change would stop "Bug Ratio Increasing Over Time" from firing again?
- What do the cited issues have in common — same root cause or same workaround?
- Who owns the two-week experiment and how will we verify on the next import?
Run this rule against your own tracker data with Flow Analyzer.