---
id: change-fail-rate
slug: /measurement/change-fail-rate
title: Change fail rate
description: Definition, collection evidence and limitations for change fail rate.
---

<div className="strategy-content">

**Target operating model — recommended contracts, not installed collection.** All owner and cadence entries below are proposals to confirm before the pilot, not assigned responsibilities or approved schedules.

**Prototype calculation — no live telemetry.** The synthetic example calculates this metric; it has no network collectors.

{/* contract:start */}
Production deployment effects requiring unplanned remediation, rollback or hotfix, not solely outage declarations.

| Contract | Definition |
| --- | --- |
| Numerator | Distinct matured production deployment_ids linked to qualifying immediate intervention |
| Denominator | All distinct production deployment_ids that reached production in the matured deployment cohort |
| Expression | N / D * 100 |
| Aggregation | percent |
| Unit | % |
| Eligible population | Deployments with production effect during window and approved intervention follow-up horizon elapsed. |
| Exclusions | Failed preproduction attempts, duplicate callbacks and no-effect retries; failures after production effect stay included. |
| Events and source | deployment.completed; deployment.failed; incident.linked; release and incident records |
| Owner / cadence | Quality Engineering / Weekly; finalized after horizon |
| Missing evidence | Known failures / all eligible deployments is a lower bound where incident linkage incomplete; label provisional and report unknown links. |
| Gaming and limits | Avoid incident links or relabel intervention planned; reconcile rollbacks/hotfixes independently. Descriptive signal, not causal AI productivity attribution. Source completeness, task mix and sampling limit inference; report uncertainty. Define immediate intervention and follow-up horizon before pilot; no universal incident-to-AI attribution. |
{/* contract:end */}

Read the shared [collection and safeguards](./collection-and-safeguards.mdx) before collecting data; see the [synthetic example and limits](./synthetic-example.mdx).

Return to [Skills Measurement](./index.mdx).

</div>