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Metric Dictionary

The canonical definition of every number we report: computation, exclusions, direction of good, the counter-metric it must be reported beside, and why it is in the set at all.

9 min readFor: Analysts, platform leads, client data ownersStage: Instrument

If a metric is not defined here, it does not go in a client scorecard. Definitions are frozen by the telemetry contract: changing one requires an amendment, both signatures, and a restatement of affected history.

Conventions

Median and p85 for every duration metric, because delivery durations are right-skewed and a mean describes outliers. Every figure carries n, the window and a query ID. Minimum reporting unit is the team; minimum survey cell size is five.

Delivery outcomes — the four keys

IDMetricDirectionCounter-metricWhy it is in the set
M-01Deployment frequencyHigherM-03Throughput and stability improve together in high performers; one without the other is not a finding
M-02Lead time for changesLowerM-12The outer-loop metric where inner-loop AI gains most often fail to appear
M-03Change failure rateLowerM-01The early warning for the instability tax — the metric DORA finds moving the wrong way under AI adoption
M-04Failed-deployment recovery timeLowerM-03Resilience under increased change volume

Flow — where the constraint lives

IDMetricDirectionNote
M-05Time to first reviewLowerAI-assisted pull requests are reported to wait several times longer for first review
M-06Review wait share of lead timeLowerConverts review latency into a share of a metric executives already track — which is how the fix gets funded
M-07Review depthWatchCounter-metric, never a target. Latency falling while zero-comment approvals rise is rubber-stamping
M-09WIP (open PRs per engineer)LowerQueueing effects dominate delivery time; AI raises arrival rate
M-10CI queue waitLowerPlatform quality decides whether AI amplifies organisational performance
M-12PR sizeLowerThe main driver of review latency and shallow review

Quality and maintainability counter-metrics

IDMetricDirectionNote
M-13Code churn rate (21-day)LowerChurn roughly doubled across the AI adoption period in a 211-million-line analysis
M-14Duplicated block rateLowerDuplication is deferred cost that no velocity metric will show you
M-16Defect escape rateLowerProduction defects per 100 merged changes
M-18Test suite flake rateLowerThe control system that keeps AI volume from becoming instability

AI attribution

IDMetricDirectionNote
M-25AI-assisted share of merged changesReported, never targetedAdoption is an input; rewarding consumption produces consumption
M-26Lead time, AI-assisted vs notLowerThe central question — and observational, because engineers choose which work to use AI on
M-27Change failure rate, AI-assisted vs notLowerLocalises the instability finding
M-28Verification load per AI-assisted PRWatchThe verification tax, costed rather than absorbed silently
M-29Provenance coverage and audited error rateHigher / lowerPublishing the error rate is what separates measurement from theatre

Metrics we deliberately exclude

ExcludedWhy
Lines of code, commits per engineerActivity metric used in isolation; AI makes it actively misleading
Token consumption, prompt counts, AI leaderboardsRewarding raw consumption is a documented trap
Suggestion acceptance rate as a success measureMeasures tool behaviour, not delivered value
Story points and velocityNot comparable across teams or time; trivially gamed
Anything at individual levelDestroys data quality and trust, permanently